Q: According to the Law of Conservation of Mass, which equation is always true for a chemical reaction?

$$\text{Total mass of reactants} = \text{Total mass of products}$$

Q: What is the correct balanced equation for the reaction: $$\_\_\_\,\text{Na}_3\text{PO}_4\,(aq) + \_\_\_\,\text{Ca(NO}_3)_2\,(aq) \rightarrow \_\_\_\,\text{NaNO}_3\,(aq) + \_\_\_\,\text{Ca}_3(\text{PO}_4)_2\,(aq)$$?

$$2\,\text{Na}_3\text{PO}_4 + 3\,\text{Ca(NO}_3)_2 \rightarrow 6\,\text{NaNO}_3 + 1\,\text{Ca}_3(\text{PO}_4)_2$$

Q: Which of the following is a precipitation reaction?

$$\text{ZnBr}_2\text{ (aq) + 2 KOH (aq)} \rightarrow \text{Zn(OH)}_2\text{ (s) + 2 KBr (aq)}$$

Q: Which of the following is the correct equilibrium expression for the reaction $$2\text{N}_2\text{O}_5 (aq) \rightleftharpoons 4\text{NO}_2 (aq) + \text{O}_2 (aq)$$?

$$K = \dfrac{[\text{NO}_2]^4 [\text{O}_2]}{[\text{N}_2\text{O}_5]^2}$$

Question 1

Which of the following is NOT an observable evidence of a chemical reaction?

Accepted Answer

Change in mass

Question 2

According to the Law of Conservation of Mass, which equation is always true for a chemical reaction?

Accepted Answer

$$	ext{Total mass of reactants} = 	ext{Total mass of products}$$

Question 3

Which of the following compounds is insoluble in water according to the solubility rules?

Accepted Answer

BaSO4

Question 4

What is the correct balanced equation for the reaction: $$\_\_\_\,	ext{Na}_3	ext{PO}_4\,(aq) + \_\_\_\,	ext{Ca(NO}_3)_2\,(aq) ightarrow \_\_\_\,	ext{NaNO}_3\,(aq) + \_\_\_\,	ext{Ca}_3(	ext{PO}_4)_2\,(aq)$$?

Accepted Answer

$$2\,	ext{Na}_3	ext{PO}_4 + 3\,	ext{Ca(NO}_3)_2 ightarrow 6\,	ext{NaNO}_3 + 1\,	ext{Ca}_3(	ext{PO}_4)_2$$

Question 5

Which of the following is a precipitation reaction?

Accepted Answer

$$	ext{ZnBr}_2	ext{ (aq) + 2 KOH (aq)} ightarrow 	ext{Zn(OH)}_2	ext{ (s) + 2 KBr (aq)}$$

Question 6

Which of the following best describes a strong electrolyte?

Accepted Answer

A compound that completely dissociates into ions in water

Question 7

Which of the following is a non-electrolyte?

Accepted Answer

C2H5OH

Question 8

What is the oxidation number of oxygen in $$	ext{H}_2	ext{O}_2 ($$hydrogen peroxide)?

Accepted Answer

$$-1$$

Question 9

In the reaction $$2	ext{Li (s)} + 	ext{Zn}^{2+} (aq) ightarrow 2	ext{Li}^+ (aq) + 	ext{Zn (s)}$$, which element is oxidized?

Accepted Answer

Li

Question 10

Which of the following changes will NOT shift the equilibrium to the left for the reaction $$	ext{CH}_4 (g) + 	ext{F}_2 (g) ightleftharpoons 	ext{CF}_4 (g) + 	ext{HF} (g)$$, $$\Delta H = +38.1 kJ/$$mol?

Accepted Answer

Decrease the temperature

Question 11

Which of the following statements about chemical equilibrium is FALSE?

Accepted Answer

At equilibrium, the concentration of reactants and products are equal.

Question 12

Given the reaction $$2	ext{NO}_2 (g) ightleftharpoons 2	ext{NO} (g) + 	ext{O}_2 (g)$$ with $$K = 1.0 	imes 10$$^{20}$$, which is present in greater amount at equilibrium?

Accepted Answer

Products

Question 13

Which of the following best describes the effect of a catalyst on a chemical reaction?

Accepted Answer

It decreases the activation energy.

Question 14

Which of the following energy diagrams represents the fastest reaction?

Accepted Answer

A diagram with the lowest activation energy (Ea)

Question 15

Which of the following is the correct equilibrium expression for the reaction $$2	ext{N}_2	ext{O}_5 (aq) ightleftharpoons 4	ext{NO}_2 (aq) + 	ext{O}_2 (aq)$$?

Accepted Answer

$$K = \dfrac{[	ext{NO}_2]^4 [	ext{O}_2]}{[	ext{N}_2	ext{O}_5]^2}$$

Question 16

Which of the following alcohols cannot undergo an oxidation reaction?

Accepted Answer

2-methyl-2-propanol

Question 17

Which of the following best describes a reduction reaction in organic chemistry?

Accepted Answer

Increase in the number of C–H bonds

Question 18

Which of the following is the correct product for the complete hydrogenation of 2-butyne ($$	ext{CH}_3	ext{C} \equiv 	ext{CCH}_3) $$with excess $$	ext{H}_2$$ and a catalyst?

Accepted Answer

Butane

Question 19

Which of the following statements about Markovnikov’s rule is correct?

Accepted Answer

The hydrogen atom adds to the carbon with more hydrogens.

Comprehensive Study Notes: Chemical Reactions and Related Concepts

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