Practice Exam Answers

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Which statement best explains the purpose of using a mole in the measurement of matter?

A
It is commonly used as another unit of mass.
B
It explains that substances with the same moles have the same mass.
C
It allows chemists to deal with a large number of atoms.
D
It is used only for studying the properties of gases.
4

Consider the reaction. 3 Mg s plus 2 cap h sub 3 PO sub 4 aq rightarrow Mg sub 3 open paren PO sub 4 close paren sub 2 s plus 3 cap h sub 2 g Which statement is true at STP? (The atomic mass of Mg is 24 point 3 1 u )

A
open paren 3 times 24 point 3 1 close paren times g of Mg produce open paren 3 times 22 point 4 close paren liters of cap h sub 2 gas.
B
24 point 3 1 g of Mg produce open paren 3 times 22 point 4 close paren liters of cap h sub 2 gas.
C
3 point 0 g of Mg produce 22 point 4 liters of cap h sub 2 gas.
D
3 point 0 g of Mg produce 3 point 0 liters of cap h sub 2 gas.
6

Which factor influences both solubility and the rate of dissolution?

A
pressure
B
particle size
C
temperature
D
nature of solvent
7

Which statement describes the law of conservation of energy?

A
Energy is destroyed in most chemical reactions when new products are formed.
B
All systems will exchange matter and energy with their surroundings.
C
All systems can exchange energy, but not matter, with their surroundings.
D
Energy cannot be created nor destroyed, but it changes from one form to another.
8

When ammonium chloride is dissolved in water, the beaker gets cold. Which type of reaction does this describe?

A
endothermic
B
neither exothermic nor endothermic
C
both exothermic and endothermic
D
exothermic
10

What overall effect does adding a catalyst have on a chemical reaction?

A
It speeds up the reaction.
B
It reduces the concentration of products.
C
It increases the concentration of reactants.
D
It slows the reaction.
11

How does an increase in reactant concentration affect the rate of reaction?

A
It leads to more frequent collisions, which increase reaction rate.
B
It leads to less frequent collisions, which increase reaction rate.
C
It leads to less frequent collisions, which decrease reaction rate.
D
It leads to more frequent collisions, which decrease reaction rate.
16

For the reaction, the order of reaction for NH sub 4 raised to the plus power is 1 , and the order of reaction for NO sub 2 raised to the negative power is 1 NH sub 4 raised to the plus A q power plus NO sub 2 raised to the negative A q power rightarrow cap n sub 2 times g plus 2 cap h sub 2 cap o l What is the rate law for the reaction?

A
cap r is equal to k open bracket NH sub 4 raised to the plus power close bracket open bracket NO sub 2 raised to the negative power close bracket
B
cap r is equal to k open bracket NH sub 4 raised to the plus power close bracket open bracket NO sub 2 raised to the negative power close bracket squared
C
cap r is equal to k open bracket cap n sub 2 close bracket open bracket cap h sub 2 cap o close bracket
D
cap r is equal to k times NH raised to the plus NO squared power
17

A weak base is added to water. Which information is required to find the strength of its conjugate acid ?

A
the value of cap k sub b and the concentration of the weak base
B
the value of cap k sub w only
C
the values of cap k sub w and and the concentration of the weak base
D
the values of cap k sub b and cap k sub w
18

Which energy changes are associated with a liquid freezing?

A
Energy is released as potential energy increases.
B
Energy is released as potential energy decreases.
C
Energy is absorbed as potential energy increases.
D
Energy is absorbed as potential energy decreases.
19

Consider the chemical equation in equilibrium. cap A times g plus 2 cap b g if and only if cap c times g plus cap d times g plus heat What will happen to the equilibrium of this reaction if the temperature is increased?

A
It will shift to the right because heat is released.
B
It will shift to the left because heat is released.
C
It will shift to the left because heat is absorbed.
D
It will shift to the right because heat is absorbed.

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