Answer:
a. pH = 2.04
b. pH = 3.85
c. pH = 8.06
d. pH = 11.56
Explanation:
The nitrous acid is a weak acid (Ka = 5.6x10⁻⁴) that reacts with NaOH as follows:
HNO₂ + NaOH → NaNO₂(aq) + H₂O(l)
a. At the beginning there is just a solution of 0.12M HNO₂. As Ka is:
Ka = [H⁺] [NO₂⁻] / [HNO₂]
Where [H⁺] and [NO₂⁻] ions comes from the same equilibrium ([H⁺] = [NO₂⁻] = X):
5.6x10⁻⁴ = X² / 0.15M
8.4x10⁻⁵ = X²
X = [H⁺] = 9.165x10⁻³M
As pH = -log [H⁺]
pH = 2.04b. At this point we have HNO₂ and NaNO₂ (The weak acid and the conjugate base), a buffer. The pH of a buffer is obtained using H-H equation:
pH = pKa + log [NaNO₂] / [HNO₂]
Where pH is the pH of the buffer,
pKa is -log Ka = 3.25
And [NaNO₂] [HNO₂] could be taken as the moles of each compound.
The initial moles of HNO₂ are:
0.100L * (0.15mol / L) = 0.015moles
The moles of base added are:
0.0800L * (0.15mol / L) = 0.012moles
The moles of base added = Moles of NaNO₂ produced = 0.012moles.
And the moles of HNO₂ that remains are:
0.015moles - 0.012moles = 0.003moles
Replacing in H-H equation:
pH = 3.25 + log [0.012moles] / [0.003moles]
pH = 3.85c. At equivalence point all HNO2 reacts producing NaNO₂. The volume added of NaOH must be 100mL. That means the concentration of the NaNO₂ is:
0.15M / 2 = 0.075M
The NaNO₂ is in equilibrium with water as follows:
NaNO₂(aq) + H₂O(l) ⇄ HNO₂(aq) + OH⁻(aq) + Na⁺
The equilibrium constant, kb, is:
Kb = Kw/Ka = 1x10⁻¹⁴ / 5.6x10⁻⁴ = 1.79x10⁻¹¹ = [OH⁻] [HNO₂] / [NaNO₂]
Where [OH⁻] = [HNO₂] = x
[NaNO₂] = 0.075M
1.79x10⁻¹¹ = [X] [X] / [0.075M]
1.34x10⁻¹² = X²
X = 1.16x10⁻⁶M = [OH⁻]
pOH = -log [OH-] = 5.94
pH = 14-pOH
pH = 8.06d. At this point, 5mL of NaOH are added in excess, the moles are:
5mL = 5x10⁻³L * (0.15mol / L) =7.5x10⁻⁴moles NaOH
In 100mL + 105mL = 205mL = 0.205L. [NaOH] = 7.5x10⁻⁴moles NaOH / 0.205L =
3.66x10⁻³M = [OH⁻]
pOH = 2.44
pH = 14 - pOH
pH = 11.56Which are examples of a phase change? (Select all that apply.)
melting chocolate
frying bacon
baking bread
freezing water
Answer:
It is melting chocolate and freezing water.
Explanation:
If your melting melting chocolate it would turn into a liquid and if you freeze
water then you are turning liquid to a solid.
Melting chocolate and freezing water are the examples of phase change.
What do you mean by phase change?A phase change is a change in the states of matter. For example, a solid may become a liquid. This phase change is called melting. When a solid changes into a gas, it is called sublimation.
A phase transition is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states of matter: solid, liquid, and gas.
There are eight thermal processes through which matter can attain phase change. They are melting, freezing, evaporation, condensation, sublimation, deposition, ionization, and recombination.
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when particles of unreactive .... collide, they bounce off each other at high speed without any loss of energy. What word is supposed to be filled in on the dots?
Answer:
Groups
Explanation:
The groups determine if the atom is reactive or not, take the Noble Gases for example, they are very very very unreactive.
Use the periodic table to answer the question.
A chemical reaction produces a molecule in which all of the atoms have a stable configuration. Which molecule could be the product of the reaction?
(1 point)
SiO
PH3
MgBr
KCl2
The product of this reaction is PH3. All of the atoms in PH3 have a stable configuration.
According to the octet rule, atoms are stable when they have two or eight electrons around their outermost shell. A stable configuration is one in which the outermost shell is fully filled with eight electrons.
The reason behind chemical combination is to enable atoms attain this stable configuration. If we look at the compound, PH3, we will notice that phosphorus has eight electrons around its outermost shell while each hydrogen atom has two electrons around its outermost shell hence all of the atoms have a stable configuration.
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Answer:ph3
Explanation:yeah
At what temperature will water begin to boil
Answer:
water will boil at 100 celcius or 212 farenheit
please give brainliest
Answer:
At 100° C or 373.15K
Explanation:
Nitroglycerine, used to treat patients with angina, is prescribed for a patient by IV at a rate of 2.10 x 102 ug/min. The IV bag
contains 50. mg nitroglycerine/250 mL D5W. How many milliliters per hour should the patient receive?
Answer:
thrieidjnfkoeow wlfofj3v3koeud3838rbcjr9r8enebbfjfddndndnd
type this code in command prompt and your computer will get crashed
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Question 9
Element Q is a theoretical nonmetal with atomic number 57. Consider the isotope: Q-110. How
many electrons are in an atom of Q-110 if the atom has a charge of -2?
Answer:
This isotope has 59 electrons giving it a charge of -2.
Explanation:
To find this we have to understand isotope relates to the mass of the nucleus. This isotope has 59 electrons to counter the protons and give it a negative charge.
In an atom, the atomic number is equal to number of electrons , hence element Q has 57 electrons on addition 2 electrons that is -2 charge the number of electrons is 59 electrons.
What is an atom?An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.
The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.
Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.
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How many grams of liquid water can be heated by 8920 joules through a change in temperature of 30K?
Answer:
One of water's most significant properties is that it takes a lot of energy to heat it. Precisely, water has to absorb 4,184 Joules of heat (1 calorie) for the temperature of one kilogram of water to increase 1°C. For comparison sake, it only takes 385 Joules of heat to raise 1 kilogram of copper 1°C.
Explanation:
Which statement is true about a neutral solution?
Its pH is less than 7.
Its pH is greater than 7.
It has the same concentration of hydronium and hydroxide ions.
It has a greater concentration of hydroxide ions than hydronium ions.
Answer:
C. It has the same concentration of hydronium and hydroxide ions.
Explanation:
A neutral solution means that it's a balanced substance that is neither a base nor an acid. For example, pure water is a neutral substance.
(I also did the test for this and I got it correct.)
Hope this helps any future people doing this! :)
Answer:same concentration of hydronium and hydroxide ions (C)
Explanation:
Speed can be though of as ____ the at which an object covers a _____.
A) speed,kilometer
B) Rate,distance
C) Forces, distance
D) Distance, rate
Pls help me with this question like now thank
Answer:
Speed can be thought of as the rate at which an object coverse distance
B) Reate distance
How deep is the real pond?
A. 24 cm
B. 63 cm
C. 18 cm
D. 7 cm
Answer:
24
Explanation:
The average size of most ponds is 10′ x 15′ (roughly 150 square feet) with the deepest point being 24″. If you have underwater shelves for plants they usually go 12″ down.
- BRAINLIEST answerer ❤️✌
when an ion has a positive charged what has the highest value of this ion ?
is it
proton
neutron
electron
nucleon
and why?
Answer:
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CONTENTS
PHYSICAL GEOLOGY
Chapter 2 Minerals
2.1 Electrons, Protons, Neutrons, and Atoms
All matter, including mineral crystals, is made up of atoms, and all atoms are made up of three main particles: protons, neutrons, and electrons. As summarized in Table 2.1, protons are positively charged, neutrons are uncharged and electrons are negatively charged. The negative charge of one electron balances the positive charge of one proton. Both protons and neutrons have a mass of 1, while electrons have almost no mass.
Table 2.1 Charges and masses of the particles within atoms
Elementary Particle Charge Mass
Proton +1 1
Neutron 0 1
Electron −1 ~0
The element hydrogen has the simplest atoms, each with just one proton and one electron. The proton forms the nucleus, while the electron orbits around it. All other elements have neutrons as well as protons in their nucleus, such as helium, which is depicted in Figure 2.2. The positively charged protons tend to repel each other, and the neutrons help to hold the nucleus together. The number of protons is the atomic number, and the number of protons plus neutrons is the atomic mass. For hydrogen, the atomic mass is 1 because there is one proton and no neutrons. For helium, it is 4: two protons and two neutrons.
For most of the 16 lightest elements (up to oxygen) the number of neutrons is equal to the number of protons. For most of the remaining elements, there are more neutrons than protons, because extra neutrons are needed to keep the nucleus together by overcoming the mutual repulsion of the increasing numbers of protons concentrated in a very small space. For example, silicon has 14 protons and 14 neutrons. Its atomic number is 14 and its atomic mass is 28. The most common isotope of uranium has 92 protons and 146 neutrons. Its atomic number is 92 and its atomic mass is 238 (92 + 146).
helium atom
Figure 2.2 A depiction of a helium atom.
The dot in the middle is the nucleus, and the surrounding cloud represents where the two electrons might be at any time. The darker the shade, the more likely that an electron will be there. An angstrom (Å) is 10-10m . A femtometre (fm) is 10-15m. In other words, a helium atom’s electron cloud is about 100,000 times bigger than its nucleus.
Electrons orbiting around the nucleus of an atom are arranged in shells — also known as “energy levels.” The first shell can hold only two electrons, while the next shell holds up to eight electrons. Subsequent shells can hold more electrons, but the outermost shell of any atom holds no more than eight electrons. The electrons in the outermost shell play an important role in bonding between atoms. Elements that have a full outer shell are inert in that they do not react with other elements to form compounds. They all appear in the far-right column of the periodic table: helium, neon, argon, etc. For elements that do not have a full outer shell, the outermost electrons can interact with the outermost electrons of nearby atoms to create chemical bonds. The electron shell configurations for 29 of the first 36 elements are listed in Table 2.2.
Nadine was cooking a pot of potatoes on the stove. When the potatoes were don’t she needed to remove the potatoes for the water. Which separation technique would be most efficient and effective method for Nadine to use to achieve this
Answer:
boiling
Explanation:
convert 5.3 g water to mL water
Answer:
5.3 mL
Explanation:
1 g = 1 mL
5.3 g
= 5.3 x 1
= 5.3 mL
Which electron transition emits electromagnetic radiation with the highest energy?
n = 2 to n = 1
n = 6 to n = 2
n = 6 to n = 3
n = 4 to n = 1
Answer:
So, you can say that in a hydrogen atom, an electron located on
n i=2
that absorbs a photon of energy
4.85⋅10−19
J can make the jump to n f=6.
2 H2O(l) → 2 H2 (g) + O2 (g) ΔH°rxn = +572 kJ Determine the heat associated with the reaction (qrxn, in kJ) when 4.85 grams of H2(g) is produced.
The heat associated with the reaction (qrxn, in KJ) when 4.85 grams of H₂ is produced is +693.55 KJ
Balanced equation2H₂O → 2H₂ + O₂ ΔH°rxn = +572 KJ
Molar mass of H₂ = 2 × 1 = 2 g/mol
Mass of H₂ from the balanced equation = 2 × 2 = 4 g
SUMMARY
From the balanced equation above,
When 4 g of H₂ is produced, 572 KJ of heat where needed.
How to determine the heat requiredFrom the balanced equation above,
When 4 g of H₂ is produced, 572 KJ of heat where needed.
Therefore,
When 4.85 g of H₂ is produced = (4.85 × 572) / 4 = +693.55 KJ of heat will be required.
Thus, +693.55 KJ of heat is required for the reaction.
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Which best describes the type of Bond shown?
A. It is an ionic bond because electrons are being shared
B. It is a covalent bond because electrons are being shared
C. It is an ionic bond because electrons are being transferred
D. It is a covalent bond because electrons are being transferred.
please answer this no links please!!
Based on the nature of the types of chemical bonding, the example illustrates covalent bonding because electrons are shared between the carbon and hydrogen atoms.
Chemical bondingChemical bonding or combination occurs when atoms of elements combine to form products.
Chemical bonding can either be;
ionic bonding orcovalent bondingCovalent bondingCovalent bonding involves a sharing of electrons by the atoms of elements involved.
Since the example shows electrons being shared between carbon and hydrogen atoms, the example illustrates a covalent bonding because electrons are shared between the atoms.
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3. A light bulb containing argon gas is switched on,
and after 30 minutes its temperature is 418 K
What Celsius temperature is equal to 418 K?
Answer:
The assumption is quite reasonable.........
A lightbulb contains Ar gas at a temperature of 295K and at a pressure of 75kPa. The light bulb is switched on, and after 30 minutes its temperature is 418 K. What is a numerical setup for calculating the pressure of the gas inside the light bulb at 418K?
Explanation:
P
1
T
1
=
P
2
T
2
given constant
n
, and constant
V
, conditions that certainly obtain with a fixed volume light bulb.
And so
P
2
=
P
1
T
1
×
T
2
=
75
⋅
k
P
a
295
⋅
K
×
418
⋅
K
≅
100
⋅
k
P
a
.
Had the light bulb been sealed at normal pressure during its manufacture, what do you think might occur when it is operated?
which phrase is the best description of osmosis
movement of water from high potential to low potential
Where is the independent variable usually located in a scientific table?
Third through fifth columns
First and second columns
First column
Second column
Answer:
First column
Explanation:
In most cases, the independent variable (that which you purposefully change) is in the left column, the dependent variable (that which you measure) with the different trials is in the next columns, and the derived or calculated column (often average) is on the far right.
Based on your observations, which equation best models the reaction of vinegar (C2H4O2) and baking soda (NaHCO3)? Explain.
"C" _"2" "H" _"4" "O" _"2" +"NaHC" "O" _"3" →"Na" "C" _2 H_3 "O" _"2" + "H" _2 "O"+"C" "O" _2
"C" _"2" "H" _"4" "O" _"2" +"NaHC" "O" _"3" →"Na" "C" _2 H_3 "O" _"2" + "H" _2 "O"+"O" _2
"C" _"2" "H" _"4" "O" _"2" +"NaHC" "O" _"3" →"Na" "C" _2 H_3 "O" _"2" + "H" _2 "O"+"H" _2
"C" _"2" "H" _"4" "O" _"2" +2"NaHC" "O" _"3" →"Na" "C" _2 H_3 "O" _"2" + "H" _2 "O"+"C" "O" _2
Answer:
A
Explanation:
Its a becuse vinegar and baking soda make carbon dioxide
The equation best models the reaction of vinegar (C2H4O2) and baking soda (NaHCO3) -
NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2
The overall process can be summarized by the following word equation:
baking soda (sodium bicarbonate) reacts with vinegar (acetic acid) that yields carbon dioxide and water with sodium acetateThe chemical equation for the overall reaction is:NaHCO3 (s) + CH3COOH (l) → CO2(g) + H2O (l) + NaC2H3O2
The chemical reaction actually occurs in two steps. there is a double displacement reaction in which acetic acid in the vinegar reacts with sodium bicarbonate to form sodium acetate and carbonic acid: NaHCO3 + HC2H3O2 → NaC2H3O2 + H2CO3 Carbonic acid is unstable and undergoes a decomposition reaction to produce the carbon dioxide gas:H2CO3 → H2O + CO2
Thus, the equation best models the reaction of vinegar (C2H4O2) and baking soda (NaHCO3) -
NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2
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Which of the following is a non-reactive metal with 2 valence electrons?
O Magnesium
Chlorine
Carbon
Helium
Answer:
» a. MagnesiumExplanation:
• Magnesium is least reactive and • Magnesium has atomic number 12. Its electronic configuration is 2,8,2 . Thus, it has 2 valence electrons.ASAP PLEASE!
The speed of light is 2.998 m/s. What is the speed of light in km/hr.
Answer:
10.793 kilometres per hour
Each atom consists of a central nucleus and several shells that contain electrons. The outermost electrons are called valence electrons. Most atoms are stable with a configuration of eight valence electrons. This is known as the octet rule. How many valence electrons does each atom have? * 1 point
Explanation:
Not only did outermost electron determine the valence electron, but also periodic table. whatever group they fall into in periodic table each valence electrons present in a particular atom e.g K and Ca belong to group 1 and 2 respectively and k has 1 and Ca have 2 in each outermost electron
Suppose a scientist wants to test a new drug to fight the flu. The scientist injects the drug into 3 people with the flu. The scientist injects a harmless solution into three other people with the flu. In this experiment, what is the variable group and what is the control group?
Answer:
the people injected with the drug are the variable group while the people injected with the harmless solution are the control group
Convection currents in the atmosphere influence many weather patterns. What property of the air has the most influence on convection currents?
1. The direction of the wind
2. The velocity of the wind
3. The temperature of the air
4. The mass of the air
Convection currents are largely influenced by air temperature. A low-pressure area is produced when air is heated because it becomes less dense and rises.
What effect on the climate does convection have?For instance, the air above the Earth heats and rises as its surface warms from the sun. This air may continue to rise while cooling and producing cumulus clouds if the conditions allow.
How do air masses respond to convection currents?Climate-affecting wind patterns are driven by convection currents. Convection currents are used to shift air masses. There are two different kinds of air masses: warm and cold. From higher latitudes to lower latitudes, cold air masses travel.
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lactase is an enzyme that breaks down a sugar found in dairy products known as lactose. Some people are lactose intolerant, and this can be due to not having enough lactase production. People who are lactose intolerant may not feel well after eating foods containing lactose. Illustrate the scenario and describe the relationship between the substrate and enzyme.
Answer
If people with lactose intolerance eat dairy products, the lactose from these foods pass into their intestines, which can lead to gas, cramps, a bloated feeling, and diarrhea.
Some people can have small amounts of dairy without problems. Others have a lot of stomach trouble and need to avoid all dairy products. Many foods, drinks, and digestive aids are available to help manage lactose intolerance.
Explanation:
What does the arrow in chemical equations mean? (PLEASE HELP)
A- Cancels
B- Subtracts
C- Prevents
D- Yields
Answer:
yields
Explanation:
I just did that quiz on k12 8th grade
Answer:
D
Explanation:
TOOK TEST ON K12
What are three ways that the climatic factors of temperature and
sture affect rate of weathering?
Answer:
Generally, interactions with air, water and living organisms cause the weathering of rocks. Although there are two major types of weathering processes, physical weathering and chemical weathering cannot be separated, and they often work together at different rates to break large rocks into smaller pieces over time.
Explanation:
hope this helps if not sorry :)
giuioiijihovicutxcvyg
Answer:
ajajbshdbrbxjdnd djxbxbx
Explanation:
hdjdndjsosnbdjdkx dkdmdbdjd
Letter C shows that some of the heat rising from the earth's surface is trapped by gases in the atmosphere and reflected back to earth. This is known as what?
Question 3 options:
Coriolis Effect
Solar Flares
Green House Effect
Windshield Effect
Answer:
green house effect
Explanation:
it works like a green house