Solutions

Molarity
Molality
% by mass
Mole fraction
Salinity

When will these people ever make up their minds????

Chemists, chemical engineers, food processors, and environmental scientists each use measurement systems which are different and convenient for themselves. So no-one can agree on what system of units should actually be used. Let’s make an analogy to building construction. Hardwood flooring is sold by the square foot, concrete is by the cubic “yard” and roofing is by the (10 foot by 10 foot) square. Another example of different units being used for convenience.

We’ll it’s no surprise Hank can enlighten us – here he’ll share with us his “Dirty Laundry”

Here are the formulas you need to know;

Molarity = (# moles solute) / (litres of solvent)

Molality = (# moles solute) / (kg of solvent)

Percent by mass = (mass of solute) / (mass of solution) x 100
note: solution is solvent + solute

Salinity = (kg salt) / (1,000 litres water)

You will find plenty of sample exercises in your reading package. You should do all the available problems before the quiz. You do not need to cover freezing point depression or boiling point elevation as we will cover these in the next lesson.

Here’s the least confusing webpage I can find on the definition of Salinity – this is from the National Snow and Ice Data Center (who would even imagine there was such a place).

Q1: What does a catalyzed soot filter do?
Q2: name 3 chenical reactions that occur in this catalytic converter, Describe the role of the catalyst in getting these reactions to happen.

Look up the catalysts in the catalytic converter of a gas automobile – look this up in your book.

Draw a table with 2 columns – in column 1 write the diesel equations, in column 2 write the gas engine equations.

Describe what diesel exhaust would look like without a catalytic converter.

Here’s a vision of the world without catalytuc converters….

CO2 is only one of many forms of pollution but here’s a list of how much waste CO2 various countries produce.

Chemistry Q3 Review

Logs and Anti logs – see worksheets


Balancing chemical reactions – see post

pH practice problems

 

Updated November 27, 2014.

A reversible chemical process is considered in equilibrium when the rate of the forward reaction equals the rate of the reverse reaction. The ratio of these reaction rates is calledthe equilibrium constant. Test your knowledge about equilibrium constants and their use with this ten question equilibrium constant practice test.

You may wish to review Chemical Equilibrium and Equilibrium Constants.

Answers appear at the end of the test.

Question 1

An equilibrium constant with a value K > 1 means:a. there are more reactants than products at equilibrium
b. there are more products than reactants at equilibrium
c. there are the same amount of products and reactants at equilibrium
d. the reaction is not at equilibrium

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Question 2

Equal amounts of reactants are poured into a suitable container. Given sufficient time, the reactants may be converted almost entirely to products if:a. K is less than 1
b. K is greater than 1
c. K is equal to 1
d. K is equal to 0

Question 3

The equilibrium constant for the reactionH2 (g) + I2 (g) ↔ 2 HI (g)

would be:

a. K = [HI]2/[H2][I2]
b. K = [H2][I2]/[HI]2
c. K = 2[HI]/[H2][I2]
d. K = [H2][I2]/2[HI]

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Question 4

The equilibrium constant for the reaction2 SO2 (g) + O2 (g) ↔ 2 SO3 (g)

would be:

a. K = 2[SO3]/2[SO2][O2]
b. K = 2[SO2][O2]/[SO3]
c. K = [SO3]2/[SO2]2[O2]
d. K = [SO2]2[O2]/[SO3]2

Question 5

The equilibrium constant for the reactionCa(HCO3)2 (s) ↔ CaO (s) + 2 CO2 (g) + H2O (g)

would be:

a. K = [CaO][CO2]2[H2O]/[Ca(HCO3)2]
b. K = [Ca(HCO3)2]/[CaO][CO2]2[H2O]
c. K = [CO2]2
d. K = [CO2]2[H2O]

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Question 6

The equilibrium constant for the reactionSnO2 (s) + 2 H2 (g) ↔ Sn (s) + 2 H2O (g)

would be:

a. K = [H2O]2/[H2]2
b. K = [Sn][H2O]2/[SnO][H2]2
c. K = [SnO][H2]2/[Sn][H2O]2
d. K = [H2]2/[H2O]2

Question 7

For the reactionH2 (g) + Br2 (g) ↔ 2 HBr (g),

K = 4.0 x 10-2. For the reaction

2 HBr (g) ↔ H2 (g) + Br2 (g)

K =:

a. 4.0 x 10-2
b. 5
c. 25
d. 2.0 x 10-1

Question 8

At a certain temperature, K = 1 for the reaction2 HCl (g) → H2 (g) + Cl2 (g)

At equilibrium, you can be certain that:

a. [H2] = [Cl2]
b. [HCl] = 2[H2]
c. [HCl] = [H2] = [Cl2] = 1
d. [H2][Cl2]/[HCl]2 = 1

Question 9

For the reaction: A + B ↔ C + D6.0 moles of A and 5.0 moles of B are mixed together in a suitable container. When equilibrium is reached, 4.0 moles of C are produced.

The equilibrium constant for this reaction is:

a. K = 1/8
b. K = 8
c. K = 30/16
d. K = 16/30

Question 10

The Haber process is a method to produce ammonia from hydrogen and nitrogen gasses. The reaction is

N2 (g) + 3 H2 (g) ↔ 2 NH3 (g)

If hydrogen gas is added after the reaction has reached equilibrium, the reaction will:

a. shift to the right to produce more product
b. shift to the left to produce more reactants
c. stop. All the nitrogen gas has already been used up.
d. Need more information.

Answers

1. b. there are more products than reactants at equilibrium
2. b. K is greater than 1
3. a. K = [HI]2/[H2][I2]
4. c. K = [SO3]2/[SO2]2[O2]
5. d. K = [CO2]2[H2O]
6. a. K = [H2O]2/[H2]2
7. c. 25
8. d. [H2][Cl2]/[HCl]2 = 1
9. b. K = 8
10. a. shift to the right to produce more product

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