Answer:
Rubidium Rb was discovered in 1861It was discovered by the German chemist Robert Wilhelm Bunsen and the German physicist Gustav-Robert KirchoffExplanation:
Rubidium was discovered by the German chemists Robert Bunsen and Gustav Kirchhoff in 1861 while analyzing samples of the mineral lepidolite with a device called a spectroscope. The sample produced a set of deep red spectral lines they had never seen before. Bunsen was eventually able to isolate samples of rubidium metal. Today, most rubidium is obtained as a byproduct of refining lithium.
Caffeine (C8H10N4O2) is a weak base with a pKb of 10.4. Calculate the pH of a solution containing a caffeine concentration of 415 mg/L .
Answer:
pH → 7.47
Explanation:
Caffeine is a sort of amine, which is a weak base. Then, this pH should be higher than 7.
Caffeine + H₂O ⇄ Caffeine⁺ + OH⁻ Kb
1 mol of caffeine in water can give hydroxides and protonated caffeine.
We convert the concentration from mg/L to M
415 mg = 0.415 g
0.415 g / 194.19 g/mol = 2.14×10⁻³ mol
[Caffeine] = 2.14×10⁻³ M
Let's calculate pH. As we don't have Kb, we can obtain it from pKb.
- log Kb = pKb → 10^-pKb = Kb
10⁻¹⁰'⁴ = 3.98×10⁻¹¹
We go to equilibrium:
Caffeine + H₂O ⇄ Caffeine⁺ + OH⁻ Kb
Initially we have 2.14×10⁻³ moles of caffeine, so, after the equilibrium we may have (2.14×10⁻³ - x)
X will be the amount of protonated caffeine and OH⁻
Caffeine + H₂O ⇄ Caffeine⁺ + OH⁻ Kb
(2.14×10⁻³ - x) x x
We make the expression for Kb:
3.98×10⁻¹¹ = x² / (2.14×10⁻³ - x)
We can missed the -x in denominator, because Kb it's a very small value.
So: 3.98×10⁻¹¹ = x² / 2.14×10⁻³
√(3.98×10⁻¹¹ . 2.14×10⁻³) = x → 2.92×10⁻⁷
That's the [OH⁻]. - log [OH⁻] = pOH
- log 2.92×10⁻⁷ = 6.53 → pOH
14 - pOH = pH → 14 - 6.53 = 7.47
How many grams of magnesium
sulfate (MgSO4) are dissolved in
0.965 L of a 0.0575 M solution?
Molar Mass Mg: 24.30 g/mol
Molar Mass S: 32.06 g/mol
Molar Mass O: 16.00 g/mol
Explanation:
Concentration question....
0.965L x (0.0575 mol MgSO4 / 1L) x (120.4g MgSO4 / 1 mol MgSO4) = 6.68g MgSO4
The concept molarity is used here to determine the grams of magnesium sulfate dissolved in 0.965 L of a 0.0575 M solution. The mass of magnesium sulfate in grams is 6.68 g.
What is molarity?The molarity of a solution is defined as the number of moles of the solute present per litre of the solution. It is generally represented by the unit mol/L. The equation used to calculate the molarity is:
Molarity = Number of moles of the solute / Volume of the solution in litres
The molar mass of MgSO₄ = 120.36 g/mol
We have 0.0575 M solution.
That is 0.0575 mol/L × 120.36 g/mol = 6.9207 g/L
Here we want mass in 0.965 L. So the mass is:
Mass = 0.965 L × 6.9207 g/L = 6.68 g
Thus the mass in grams of magnesium sulfate is 6.68 g.
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No links.
Calculate the pH and pOH of each solution.
a) [H + ] = 1.7 x 10 -8M
b) [H + ] = 1.0 x 10 -7M
Explanation:
first find the value of Ph
from Ph= -log[H+]
ph=-log[1.7x10^-8]=7.769
find Poh from 14=ph+poh
14=7.769+poh
Poh=6.231 part a
for part b the same as part a from the above procedure
The hammerhead shark can reproduce both sexually and asexually. What characteristic of the offspring would suggest that they were produced
through sexual reproduction? Offspring are-
all the same gender.
genetically diverse.
produced in small number.
produced very slowly.
Answer: I think it is ‘Genetically diverse’
Explanation:
A student makes several observations about a plece of iron. Which observation describes a chemical property of the Iron?
Answer:rust
Explanation:
PLEASE HELP I SCORED A 20%
What is the function of the outer covering of a plant?
A plant's outer covering is involved in reproduction.
A plant's outer covering helps reduce water loss.
A plant's outer covering is for preying on other plants.
A plant does not have an outer covering.
Answer:b
Explanation:
The function of the outer covering of a plant is to help reduce water loss, option B. The outer covering of a plant is known as the epidermis, and it serves as a protective layer that helps to prevent excessive water loss through transpiration.
What is plant's epidermis ?The epidermis may contain specialized structures such as stomata and trichomes, which further regulate water loss and protect the plant from environmental stresses such as insect predation and UV radiation.
Option A, "A plant's outer covering is involved in reproduction," is incorrect because the reproductive structures of plants are typically located within the plant's interior, not on the outer surface.
Option C, "A plant's outer covering is for preying on other plants," is incorrect because plants are not capable of actively preying on other plants.
Option D, "A plant does not have an outer covering," is incorrect because all plants have an outer covering in the form of the epidermis or a similar structure.
Hence, option B is correct.
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what ive learned about heat,sound and light
Answer:
they are all in parts of our life and we need them each for surviving.
Explanation:
pls help will give brainless
If the prescribed dosage of milk of magnesia Mg(OH)2 is 3.5 moles, how many grams
would you need to take? Round to the nearest tenth (one digit after the decimal).
A. 92.1 g
B. 204.2g
C. 157.2 g
D. None of the above
Answer:
B
Explanation:
1 mole is equal to 58.31968 grams.
so 3.5 moles equal to answer choice B
How many joules of heat are required to raise the temperature of 320.0 grams of water from 24.2°C to 50.8°C? Heat capacity of water is 4.2 J/g°C.
Answer:
35750.4 Joules
Explanation:
Using the formula as follows;
Q = m × c × ∆T
Where;
Q = amount of heat (joules)
m = mass of substance (g)
c = specific heat capacity (J/g°C)
∆T = change in temperature (°C)
According to the provided information,
mass (m) = 320.0 grams
c = 4.2 J/g°C
∆T = (50.8°C - 24.2°C) = 26.6°C
Q = ?
Using; Q = m × c × ∆T
Q = 320 × 4.2 × 26.6
Q = 35750.4 J
PLEASE HELP!! 15 POINTS!
What could the fourth quantum number of a 2s^2 electron be?
Answer:
option D
Explanation:
first quantum number of a 2s2
n = 2
second quantum number of a 2s2
l = 0 to n-1
l = 0, 1
For s orbital
l = 0
third quantum number of a 2s2
ml = - l to +l
ml = 0
fourth quantum number of a 2s2 electron be
?½ = spin down
½ = spin up
2s2 has 2 electrons 1 spin down and 1 spin up (starts with spin down)
ms = +1/2
Answer:
+1/2
Explanation:
which one is more soluble C12H22O11 or MgCl2 and why?
Answer:
MgCl2
Explanation:
because of the salt containing Cl
A sample of 1.00 moles of oxygen at 50°C and 98.6 kPa, occupies what volume?
Answer:
27.22 dm³
Explanation:
Given parameters:
number of moles = 1 mole
temperature= 50°C, in K gives 50+ 273 = 323K
Pressure= 98.6kpa in ATM, gives 0.973 ATM
Solution:
Since the unknown is the volume of gas, applying the ideal gas law will be appropriate in solving this problem.
The ideal gas law is mathematically expressed as,
Pv=nRT
where P is the pressure of the gas
V is the volume
n is the number of moles
R is the gas constant
T is the temperature
Input the parameters and solve for V,
0.973 x V = 1 x 0.082 x 323
V= 27.22 dm³
Type the correct answer in each box.
Balance the equation.
_____SiO2 + ______CaC2 → _____Si + _______CaO + _____CO2
The balanced equation of the given reaction is as follows: 5SiO2 + 2CaC2 → 5Si + 2CaO + 4CO2.
How is an equation balanced?A chemical equation is said to be balanced when the number of atoms of each element on both sides of the equation is the same.
According to this question, a chemical reaction between quartz and calcium chloride is given to produce silicon, calcium oxide and carbon dioxide.
The balanced equation that represents an equal number of atoms on both sides is as follows:
5SiO2 + 2CaC2 → 5Si + 2CaO + 4CO2
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A hot air balloon rises because the fire warms up the air and the air circulates to fill the balloon and lift it at the same time. What type of heat transfer is this?
Answer:
convection
Explanation:
Convection is a mode of heat transfer in which the particles of a substance actually move from place to place.
During convection, warmer and less dense air rises while colder and denser air sinks downwards under gravity.
Hence; when hot air balloon rises because the fire warms up the air and the air circulates to fill the balloon and lift it at the same time, convection has taken place.
Define stoichiometry
Stoichiometry is the field of chemistry that is concerned with the relative quantities of reactants and products in chemical reactions. For example, when oxygen and hydrogen react to produce water, one mole of oxygen reacts with two moles of hydrogen to produce two moles of water
Answer:
the relationship between the relative quantities of substances taking part in a reaction or forming a compound, typically a ratio of whole integers.
Explanation:
Dont put so much points pal,
What are these means in Periodic Table;
Group
Period
Block
Which pair of compounds represents one Arrhenius acid and one Arrhenius base?
1. CH3OH and NaOH
2. HNO3 and NaOH
3. CH3OH and HCI
4. HNO3 and HCI
Answer: C HNO3 and NaOh
Explanation:
What is the difference between an exoplanet and a pulsar
Answer:
exoplanet: a planet that orbits a star outside the solar system.
pulsar: a celestial source of pulsating electromagnetic radiation (such as radio waves)
Explanation:
exoplanet: a planet that orbits a star outside the solar system.
pulsar: a celestial source of pulsating electromagnetic radiation (such as radio waves)
PPPPPLLLLLZZZZZZ HHHHEEEELLLLLLPPPPPP!!!!!!!!!! QUESTION IS BELOW! :D
Answer:
Explanation:
Both points on a wave oscillate in directions that are perpendicular to the wave's advanced path, resulting in a transverse wave motion. Sea surface ripples, seismic S (secondary) waves, and electromagnetic (e.g., radio and light) waves are examples of transverse waves.
Their frequency and amplitude are related to the amount of energy they bear. The more energy, the higher the frequency, and the more energy, the higher the amplitude. With the activity Investigating waves and electricity, you will create these patterns on your own.
Particles in the medium vibrate to and from in a direction perpendicular to the direction of energy transport in transverse waves.
(hope this helps can i plz have brainlist :D hehe)
an amount of 54.11 grams of pentane, c5h12 ,is equal to
2
In the movie, Tim says that Saturn's rings refract light to
produce colors. What does this mean?
A They emit light
B They bend and reflect light
CThey absorb all light
D They block light
Answer:
It would be B they bend to reflect light
Can someone please help me with my chemistry hw
Answer:
a) 18
b)288g
Explanation:
a) 1:4
4.5mol TiCl4 so HCl is 4(4.5mol)
b) mm of HCl is 36
because 1:4 we multiply 2.0 mol by 4
8mol of HCl
we multiply 8mol by 36 (molar mass of HCl) and we get 288g because mol×molar mass= grams
Which of the following is true about limiting and excess reagents?
Links are reported
Answer:
the first one
Explanation:
I take this subject
please help me this is due very soon
Answer:
the answer is a because thermal energy is heat and the question said that is not a factor of thermal energy so A does not refer to heat
bismuth (V) nitrate + strontium hydroxide
Answer: [tex]2Bi(NO_3)_5(aq)+5Sr(OH)_2(aq)\rightarrow 2Bi(OH)_5(s)+5Sr(NO_3)_2(aq)[/tex]
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
A double displacement reaction in which one of the product is formed as a solid is called as precipitation reaction.
The balanced chemical equation is:
[tex]2Bi(NO_3)_5(aq)+5Sr(OH)_2(aq)\rightarrow 2Bi(OH)_5(s)+5Sr(NO_3)_2(aq)[/tex]
Infer why the sauce on a hot pizza burns your
mouth but the crust of the pizza does not burn
your mouth.
The cheese having a higher thermal conductivity conducts heat better so it can deliver the heat to your mouth more quickly while the pizza crust transmits heat more slowly. So, even if they were the same temperature, the cheese would more likely give your tongue/mouth a severe burn.
BRAINLIEST WILL BE GIVEN, PLZ HELP + 15 PTS
Which properties are characteristic of true solutions? (Select all that apply.)
The light beam is unaffected.
The particles are larger than 10 -8 cm.
The particles are dissolved.
The particles are suspended indefinitely.
Answer:
The correct answer is the last option
Explanation:
HURRY WILL GIVE BRAINLIETS How are proteins and nucleic acids related? They both provide energy. They both carry genetic information. The structure of proteins is determined by nucleic acids. The subunits of nucleic acids are also the subunits of proteins.
Answer: the answer is “C”
Explanation:
Took the T E S T
Explain what happens when salt used for snow causes metallic parts of a car to corrode. What is the process called?
Answer:
Why does a car rust from road salt? Metal parts of a car come in contact with precipitation water containing carbon dioxide and oxygen. Road salt contains free-radical ions and they come into contact with the precipitation water. After extended exposure to oxygen, iron oxide forms, which speeds up the rusting process.
Explanation: