b. The heat of reaction for the process described in (a) can be determined by
applying Hess's law. The heats of reaction shown in the table below can be
obtained experimentally or looked up in tables of enthalpy data. Which two of
these heats of reaction would be the easiest and safest to measure in the
laboratory, and which two are better obtained through reference sources?
Why? Hint: Consider whether a reaction takes place in aqueous solution or
instead involves noxious gases.
Answer: I believe the 1st and 3rd reactions are better obtained through reference sources and the 2nd and 4th are easiest and safest to measure in the laboratory.
Explanation:
I am also working on this Pre-lab right now, and I looked back at the first question to help get my answer. In the first question (a), it is noted that ammonia gas and gaseous hydrochloric acid are both potentially dangerous in gaseous form. I saw that both the 1st and 3rd reactions contained noxious gases (I knew this because there was a (g) in both of these reactions). Using the knowledge from the first question that the noxious gases were potentially dangerous, I assumed that those reactions were the ones that are better obtained through the reference sources. The 2nd and 4th reactions did not contain any noxious gases, so I assumed those ones were easiest and safest to measure in the laboratory. Hope this helps!
please help me im literally so confused
Answer:
A
Explanation:
Mark me brainliest pls
help me, it’s pretty easy science moon stuff !
We observe that 0.123 mole of the element bromine combines with 0.123 mole of the element lead to form a compound. What is the empirical formula for the compound?
The empirical formula of the compound with 0.123 moles of bromine and 0.123 moles of lead would be PbBr.
Empirical formula determinationThe empirical formula of a compound is the chemical formula of the compound where the component atoms are in their simplest, whole-number ratios.
In this case, the compound contains bromine and lead:
Br = 0.123 mole
Pb = 0.123 mole
Dividing through by the smallest mole
Br = 0.123/0.123 = 1
Pb = 0.123/0.123 = 1
Thus, bromine and lead are present in a 1:1 ratio in the chemical formula.
In other words, the empirical formula of the compound containing 0.123 moles of bromine and 0.123 moles of lead is PbBr.
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What is the density (using proper sig figs) of a rock with a volume of 6.7 mL and a mass of 12.34 grams?
Density is an intensive property as it does not depend on the quantity of the substances Whereas mass and volume are extensive property. Therefore, the density of a rock with a volume of 6.7 mL and a mass of 12.34 grams is 1.841g/ml.
What is density?Density tells about the compactness of the substances, how much dense is the substances in other words. Object that is more denser than water they just sink in the water.
Mathematically,
Density of rock = Mass of the rock ÷volume marked on the graduated cylinder
volume of rock= 6.7 mL
mass of rock= 12.34 grams
Substituting all the values in above formula, we get
Density of rock= 12.34 grams÷6.7 mL
=1.841g/ml
Therefore, the density of a rock with a volume of 6.7 mL and a mass of 12.34 grams is 1.841g/ml.
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like tobacco smoke, the aerosol given off by an e-cigarette can contain dangerous chemicals.
Yes, the aerosol given off by an e-cigarette can contain dangerous chemicals, such as nicotine, ultrafine particles, volatile organic compounds, and heavy metals.
Inhaling these chemicals can increase the risk of lung and heart disease.
E-cigarettes are becoming increasingly popular as an alternative to tobacco-based cigarettes. However, many people are unaware of the potential dangers associated with using e-cigarettes. The aerosol produced by e-cigarettes can contain not only nicotine, but also other chemicals and particles that can be harmful to the user’s health. These include ultrafine particles, volatile organic compounds, and heavy metals such as lead and nickel.
When these particles and chemicals are inhaled, they can cause inflammation and irritation of the lungs and airways, leading to a variety of respiratory illnesses.
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Thermal energy always moves from _ _ _ _ to _ _ _ energy.
Fill in the blanks.
Thermal energy always moves from higher energy area to lower energy area over a temperature gradient.
What is thermal energy?Thermal energy is a form of energy by virtue of temperature of a body. As the temperature of a body increase its thermal energy increases. Thermal energy or heat energy transfers though medium and vacuum from higher energy area to lower energy area.
Heat transfer can be through conduction in solids, convection in fluids and by radiation through space. In conduction, the thermal energy easily transfers through a chain of close packed molecules.
In all these mode of heat transfer heat energy is flowing from a hotter region to a colder region.
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In a titration experiment, a 12.5 mL sample of 1.75 x 10^-2 M Ba(OH) 2 just neutralized 14.5 mL of HNO 3 solution. Calculate the molarity of the HNO 3 solution.
The number of moles must be equal, the ratio of the molarity of each must be equal to the ratio of the volumes used.
What is experiment?An experiment is a procedure or set of procedures used to test a hypothesis or explore a cause and effect relationship. It is a scientific method of investigation in which the investigator manipulates one or more independent variables and measures the subsequent effect on one or more dependent variables. Experiments are conducted to answer questions, test theories, and gain insight into cause-and-effect relationships.
The molarity of the HNO 3 solution can be calculated using the equation:
Molarity of HNO3 = (volume of HNO3 * molarity of Ba(OH)2) / volume of Ba(OH)2
Molarity of HNO3 = (14.5 mL * 1.75 x 10^-2 M) / 12.5 mL
Molarity of HNO3 = 1.4 x 10^-2 M
This equation works because the number of moles of HNO3 neutralized by the Ba(OH)2 must be equal to the number of moles of Ba(OH)2 used. The number of moles of each can be determined by multiplying the molarity of each by the volume used, and since the number of moles must be equal
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The photoelectron spectrum for the element nitrogen is represented above. Which of the following best explains how the spectrum is consistent with the electron shell model of the ato
f the atom?
A. The leftmost peak represents the valence electrons.
B. The two peaks at the right represent a total of three electrons.
C. The electrons in the ls sublevel have the smallest binding energy
D. The electrons in the 2p sublevel have the smallest binding energy
The electrons in the 2p sub level have the smallest binding energies, which is the best explanation for how the spectrum is consistent with the electron shell model of the atom. Option D is correct as a result.
Photoemission spectroscopy, often referred to as photoelectron spectroscopy, measures the amount of energy emitted by electrons from solids, gases, or liquids via the photoelectric effect. This procedure involves getting the energy for the electrons from an outside source, such as sunlight.
The photoelectric effect is a process in which electrons receive energy from an external source, such as sunlight, become excited, and transition from the ground state to the excited state. As a result of this process, there is a constant flow of electrons, which in turn causes a flow of energy.
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For each of the following balanced chemical equations, write all possible mole ratios: a. 2Ca + O2 ⎯→ 2CaO b. Mg + 2HF ⎯→ MgF2 + H2
The mole ratio of the reactants and products is
a. 2 : 1 : 2
b. 1: 2:1:1
The ratio of the mole quantities of any two compounds present in a balanced chemical reaction is known as the mole ratio. A comparison of the ratios of the molecules required to accomplish the reaction is given by the balancing chemical equation. The coefficients of each species in the reactants and products are used to calculate the mole ratio of the reactants and products. The mole ratio of the reactants and products, as demonstrated by the equation in the question, is 2: 1: 2 and 1:2:1:1 respectively.
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Place the following molecules in order of decreasing bond angle: NH3, CO2, CCl4, OF2
O CO2 > CCl4 > NH3 > OF2
O NH3 > CO2 > CCl4 > OF2
O CO2 > CCl4 > OF2 > NH3
O CCl4 > CO2 > OF2 > NH3
O OF2 > NH3 > CCl4 > CO2
The order of decreasing bond angle for the given molecules is :
O OF2 > NH3 > CCl4 > CO2
In molecules with a central atom, the bond angle is determined by the electron pair-bond pair repulsion. The bond angle decreases as the number of electron pair-bond pair increases. In OF2 the central atom is O, and it has 2 lone pairs and 2 single bonds, the bond angle is expected to be smaller than in the other molecules.In NH3, the central atom is N, and it has 3 single bonds and 1 lone pair, the bond angle is expected to be larger than in OF2 but smaller than in CO2 and CCl4. In CO2 and CCl4, the central atoms are C and Cl respectively, and they have 4 single bonds and no lone pairs, the bond angle is expected to be larger than in NH3, but smaller than in OF2.
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A 35.2-mL, 1.66 M KMnO 4 solution is mixed with 16.7 mL of 0.892 M KMnO 4 solution. Calculate the concentration of the fi nal solution.
The concentration of the final solution is 1.41[tex]\frac{mol}{L}[/tex].
Now, first calculate the number of moles of first solution:
[tex]M_{1} =\frac{no. of moles of solution}{total volume of solution}[/tex]
no. of moles we have to find
total volume is 0.0352L and molarity of solution is 1.66M
The total number of moles of solute present in a given solution per litre is known as its molarity. In contrast to mass, which varies as the system's physical circumstances vary, the volume of a solution changes as a function of changes in the system's physical qualities, such as pressure and temperature. This has an impact on the molality of the solution. The symbol M, sometimes known as a molar, denotes molarity.
[tex]1.66=\frac{n}{0.0352}[/tex]
on solving we get,
n=0.0584 mol
Now, find the number of moles of second solution by the same formula used to find the moles of first solution,
molarity of second solution is 0.892M and total volume is 0.0167L
Now, put the values in the formula,
[tex]0.892=\frac{m}{0.0167}[/tex]
On solving we get,
m=0.0149 mol
and to find the concentration of new solution number of moles is equal to the sum of moles of first solution and second solution.
x=m+n
x=0.0584+0.0149
x=0.0733 mol
Now, molar concentration is,
[tex]M=\frac{x}{V}[/tex]
[tex]M=\frac{0.0733}{0.352+0.0167}[/tex]
On solving we get,
M=1.41[tex]\frac{mol}{L}[/tex]
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What is Gay- Lussacs law? State the definition of law in your own words.
how many grams of C are in 500g or NaHCO3
Answer: 71.43g
Explanation: The RMM of NaHCO3 is
23+1+12+16(3)=84.
There is one carbon in NaHCO3 thus there are 1×12g of C in NaHCO3.
Thus
85gNaHCO3-----12g C
500gNaHCO3---- xgram
(500×12)÷84= 71.43
Please help, no link please.
Answer:
C if not A
Explanation:
3. What volume would be occupied by 3.5 mol of oxygen gas at a pressure
of 768 mm Hg and a temperature fo 25°C?
SHOWING WORK
NO FILES PLZ
Answer:
The oxygen will occupied 84.7 L.
Explanation:
Ideal gases are a simplification of real gases that is done to study them more easily. It is considered to be formed by point particles, do not interact with each other and move randomly. It is also considered that the molecules of an ideal gas, in themselves, do not occupy any volume.
The pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:
P*V = n*R*T
where P is the gas pressure, V is the volume that occupies, T is its temperature, R is the ideal gas constant, and n is the number of moles of the gas. The universal constant of ideal gases R has the same value for all gaseous substances.
In this case:
P= 768 mmHgV= ?n= 3.5 molR= 62.36 [tex]\frac{mmHg*L}{mol*K}[/tex]T= 25 C= 298 K (being 0 C= 273 K)Replacing:
768 mmHg* V= 3.5 mol* 62.36 [tex]\frac{mmHg*L}{mol*K}[/tex] *298 K
Solving:
[tex]V=\frac{3.5 mol*62.36\frac{mmHg*L}{mol*K}*298 K }{768 mmHg}[/tex]
V= 84.7 L
The oxygen will occupied 84.7 L.
What element was oxidized and reduced in this reaction and what is the oxidizing and the reducing agent for this reaction? Au(NO3)3 + Cu ——> Cu(NO3)2 + Au
Answer: Cu is oxidized while Au is reduced. The oxidizing agent is Au while the reducing agent is Cu
Answer:
Both blanks are "Ag"
(:
Explanation:
How many ATP does glycolysis produce 4 ATP?
Energy is released when glycolysis occurs, and this energy is utilized to create four molecules of ATP. As a result, glycolysis produces a net gain of two ATP molecules.
What is glycolysis?The metabolic mechanism that transforms glucose to pyruvate is known as glycolysis. This free energy is utilized to create the high-energy molecules adenosine triphosphate and reduced nicotinamide adenine dinucleotide. Glycolysis is a series of 10 enzyme-catalyzed processes. The initial stage in the breakdown of glucose to extract energy for cellular metabolism is glycolysis. Glycolysis is divided into two phases: energy-requiring and energy-releasing. Glycolysis is the process of breaking down glucose to create energy. It generates two pyruvate molecules, ATP, NADH, and water. The process occurs in a cell's cytoplasm and does not require oxygen. It can be found in aerobic and anaerobic organisms.
Here,
When glycolysis happens, energy is released, and this energy is used to build four molecules of ATP. As a result of this, glycolysis generates a net gain of two ATP molecules.
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Draw the structure for the product of the reaction between 2-butene and hydroiodic acid, HI.
The product of the reaction between 2-butene and hydroiodic acid (HI) is 2-iodobutane.
The reaction mechanism involves a nucleophilic substitution, where the iodine atom in HI acts as the nucleophile and attacks the carbon atom in the double bond of 2-butene. This results in the formation of a carbocation intermediate, which then undergoes a rearrangement to form 2-iodobutane. The overall reaction can be represented as follows: 2-butene + HI → 2-iodobutane + H2.Nucleophilic substitution is a type of chemical reaction in which a nucleophile (a molecule or ion with a lone pair of electrons) attacks an electron deficient species, known as an electrophile, to form a new chemical bond. In the process, the electrophile's original electron pair is replaced by the nucleophile. Nucleophilic substitution reactions can occur in a variety of ways, such as S N 1, S N 2, and S Ni (where i = 1, 2, or any other number).
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Eighth grade > F.5 Compare physical and chemical changes B6V What do these two changes have in common? burning food on a stove deep-frying chicken Select all that apply. Both are only physical changes. Hoth are chemical changes. Both conserve mass. Both are caused by heating.
Answer:
both are caused by heating
Indicate whether each of the following molecules is capable of geometrical (cis-trans) isomerism. Check all that apply. O 1,3-dichloro-2-butene O 1,4-dichlorobenzene O 1,1-dichloro-1-butene O 4,5-dimethyl-2-pentyne
1,3-dichloro-2-butene and 1,1-dichloro-1-butene.Geometrical isomerism, also known as cis-trans isomerism, occurs when a molecule has two or more structural isomers that differ in the spatial arrangement of the atoms.
Cis-trans isomerism is only possible when the molecule has at least one carbon-carbon double bond. In this type of isomerism, the two isomers differ in the orientation of the substituent groups around the double bond. 1,3-dichloro-2-butene and 1,1-dichloro-1-butene both contain a carbon-carbon double bond and are therefore capable of geometrical isomerism. 1,4-dichlorobenzene does not contain a carbon-carbon double bond and therefore is not capable of geometrical isomerism. 4,5-dimethyl-2-pentyne also does not contain a carbon-carbon double bond and is therefore not capable of geometrical isomerism.
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Which of the following statements correctly identifies the decomposition reaction and describes a substance involved
Option C. Decomposition reaction: a substance involved is oxygen.
A decomposition reaction is a type of chemical reaction in which a single compound breaks down into two or more simpler substances.Decomposition Reaction Involving OxygenA decomposition reaction is a type of chemical reaction where a single compound is broken down into two or more simpler substances. In the reaction, energy is typically used to break down the bonds that hold the molecules of the compound together. Oxygen is often a substance involved in the reaction, as it is used to provide the energy needed to break down the compound. When oxygen is involved, the reaction is sometimes referred to as an oxidation reaction.
Since the question is not complete, here's the full task:
Which of the following statements correctly identifies the decomposition reaction and describes a substance involved?
Choose the right option:
A. Combustion reaction: a substance involved is oxygen
B. Combustion reaction: a substance involved is a hydrocarbon
C. Decomposition reaction: a substance involved is oxygen
D. Decomposition reaction: a substance involved is a hydrocarbon
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Matter with a ___ luster reflects little light from its surface.
Fill the blank
Matter with a Dull luster reflects little light from its surface.
Minerals with dull luster reflect very little light.
What is Luster?The term "luster" refers to the light reflection from a mineral's surface. To define lustre, mineralogists use specific terminology. The mineral's metallic or non-metallic nature can be used to categorise lustre in a straightforward manner. Metallic lustre can be seen in opaque, sparkling minerals like pyrite. Quartz is one example of a mineral with a non-metallic shine.
Metallic lustre denotes a sheen akin to polished metal. Clean, polished chunks of chrome, steel, titanium, copper, and brass, as well as many other minerals, all have a metallic shine. The most prevalent nonmetallic lustre is glassy, which denotes that the mineral's surface reflects light like glass. The most typical sort of mineral, feldspars, must have a pearly shine to be recognised. Similar to how pearls reflect light, pearly lustre describes a delicate iridescence or colour play in the reflected light. To reflect light with a silky sheen is to be silky. The sheen of hardened bacon fat is comparable to that of grease.Light is reflected relatively little by minerals with a poor sheen. It takes a little practise to spot lustre. Keep in mind to separate shine from colour.What is Dull Luster?Due to their coarse granulations, which scatter light in all directions and resemble a Lambertian reflector, dull (or earthy) minerals have little to no shine. Kaolinite is one Example.
Different types of non-metallic lusterLuster Appearance
Adamantine Sparkly
Earthy Dull, clay-like
Pearly Pearl-like
Resinous Like resins, such as tree sap
Silky Soft-looking with long fibers
Vitreous Glassy
What are Minerals?Minerals are inorganic solids that exist in nature and have a distinct chemical composition and crystal lattice structure. Even though thousands of minerals in the earth have been found, only ten minerals—plagioclase, quartz, orthoclase, amphibole, pyroxene, olivine, calcite, biotite, garnet, and clay—make up the majority of the crust's volume.
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(05.04 LC)
How many moles of sulfuric acid (H₂SO4) are needed to react completely with 6.8 moles of lithium hydroxide (LiOH)?
2LIOH + H₂SO4 → Li2SO4 + 2H₂O
O 3.4 mol H₂SO4
O 6.8 mol H₂SO4
O 10.2 mol H₂SO4
O 13.6 mol H₂SO4
3.4 mole of H₂SO₄ are needed to react completely with 6.8 moles of lithium hydroxide (LiOH).
Is lithium hydroxide harmful to humans?When breathed in, lithium hydroxide monohydrate can have an impact on you. Lithium Hydroxide Monohydrate is a HIGHLY CORROSIVE CHEMICAL, and contact with it can cause serious skin irritation, eye damage, and burning. Lithium Hydroxide Monohydrate inhaled can irritate the throat and nose.
From the stichiometry of the reaction: 2 LiOH + H2SO4 → Li2SO4 + 2H2O
It is evident that 2.0 moles of LiOH reacts with 1.0 mole of H2SO4 to produce 1.0 mole of Li2SO4 and 2.0 moles of H2O.
Using cross multiplication:
1.0 mole of H2SO4 reacts completely with → 2.0 moles of LiOH
x mole of H2SO4 are needed to react completely with → 6.8 moles of LiOH
since number of moles of H2SO4 = ( 1.0 x 6.8 ) / (2.0) = 3.4 mole of H2SO4.
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BRAINLIEST!!HELP PLEASEEEE2. Use the following chemical equation to answer the question.
4K(s) + O2(g) → 2 K20 (s)
If a staff member at a laboratory has 12. 0 grams of potassium metal, what is the
theoretical yield of potassium oxide (K2O) that the scientist could potentially
produce from the reaction with oxygen gas?
If a laboratory employee has 12.0 grammes of potassium metal, the theoretical yield of potassium oxide that even the scientist may theoretically make from the reaction with oxygen gas is 14.5 gram of K2O.
In chemistry, yield, also known as reaction yield, is a measurement of the number of moles of a product created in ratio to the reactant consumed in a chemical reaction, generally represented as a percentage. Before performing chemical reactions, it is necessary to know how many product will be produced with certain reactant quantities. This is referring to the theoretical yield.
This approach is useful for calculating the theoretical yield of such a chemical process. The yield of a reaction represents how much product is generated by that reaction. The theoretical yield is the amount of product predicted by stoichiometry, whereas the actual yield is the amount produced.
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What is true of a chemical reaction?a. Products and reactants must be balanced.
b. Subscripts must be used with all products and reactants
c. Energy must be included in the beginning of the reaction
d. Coefficients must be used with all products and reactants
Answer: The product and reactant must be balanced
Explanation:
What happens when light hits the pigment in photosystem II?
Answer:
The most common and abundant pigment is chlorophyll a. A photon strikes photosystem II to initiate photosynthesis. Energy travels through the electron transport chain, which pumps hydrogen ions into the thylakoid space. This forms an electrochemical gradient.
Which type is a metamorphic rock formed from shale
- Slate
- Sandstone
-Limestone
-Gneiss
slate is the correct answer i PROMISE
(. ^ ᴗ ^.)
Indicate whether F3C−C≡N is linear, planar, or neither.
O linear
O planar
O neither linear nor planar
Left C would be neither linear and neither planar since, in accordance with the preceding definition, it has a tetrahedral form.
Which is better, planar or non-planar?Since no links cross one another, graph A is planar. Because so many connections overlap, graph B is not plane. Additionally, graph B's linkages cannot be rearranged in a way that makes it planar.
How does one recognize planar?A compound is said to be planar if every atom inside it is located on the same plane. - Take the organic compound, for example. When the carbon atoms of an organic molecule lay within a single plane, the complex is referred to as a planar compound.
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A 36-gram sample of water has an initial temperature of 220C. After the sample absorbs 1200 joules of heat energy, the final temperature of the sample is
The specific heat of water is equal to 1200 joules / (36 grams × (240C - 220C)) = 16.7 joules/gram・°C.
What is temperature?Temperature is a measure of the average kinetic energy of the particles in a material. It is measured in degrees on the Celsius, Kelvin and Fahrenheit scales. Temperature is an important factor in many physical and chemical processes, such as the rate of chemical reactions, the speed of sound, the intensity of light and the properties of gases.
The specific heat of water, c, is calculated using the equation c = Q / (m × ΔT), where Q is the amount of heat energy, m is the mass of the sample and ΔT is the change in temperature.
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