Question 1

Which of the following best describes a combustion reaction?

Accepted Answer

A reaction where a hydrocarbon reacts with oxygen to produce carbon dioxide and water.

Question 2

In the chemical equation $2Mg(s) + O_2(g) \rightarrow 2MgO(s)$, what does the symbol $(s)$ represent?

Accepted Answer

Solid

Question 3

Which of the following is the correct balanced equation for the reaction of aluminum with nickel(II) ions to produce aluminum ions and nickel metal?

Accepted Answer

$2Al(s) + 3Ni^{2+}(aq) \rightarrow 2Al^{3+}(aq) + 3Ni(s)$

Question 4

According to the Law of Conservation of Mass, which of the following must be true for a balanced chemical equation?

Accepted Answer

The total number of atoms of each element must be the same on both sides.

Question 5

What is the limiting reactant when 13.1 g of Mg reacts with 13.6 g of $O_2$ according to $2Mg(s) + O_2(g) \rightarrow 2MgO(s)$?

Accepted Answer

Magnesium

Question 6

How many grams of $NH_3$ can be formed from 7.53 g of $H_2$ (with excess $N_2$) in the reaction $N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)$? (Molar masses: $H_2 = 2.02$ g/mol, $NH_3 = 17.03$ g/mol)

Accepted Answer

63.5 g

Question 7

Which of the following best describes a double displacement (metathesis) reaction?

Accepted Answer

A reaction where two compounds exchange ions to form two new compounds.

Question 8

What is the percent yield if the theoretical yield of $MgO$ is 21.7 g and the actual yield is 12.4 g?

Accepted Answer

$57.1\%$

Question 9

A 128.3 mg sample of limestone yields 140.2 mg of $CaC_2O_4$ after reaction and isolation. What is the mass percent of calcium in the limestone? (Molar mass $CaC_2O_4 = 128.1$ g/mol, $Ca = 40.08$ g/mol)

Accepted Answer

$43.8\%$

Question 10

Which symbol in a chemical equation indicates that a substance is dissolved in water?

Accepted Answer

$(aq)$

Question 11

In a titration, what is the equivalence point?

Accepted Answer

The point where the amount of titrant added is stoichiometrically equivalent to the amount of analyte.

Question 12

Which of the following is a decomposition reaction?

Accepted Answer

$2H_2O_2(g) \rightarrow 2H_2O(l) + O_2(g)$

Question 13

If 51.7 mL of 0.145 M $KMnO_4$ is required to titrate a 20.0 g sample of $H_2O_2$, what is the percent by mass of $H_2O_2$ in the sample? (Molar mass $H_2O_2 = 34.02$ g/mol)

Accepted Answer

$6.41\%$

Question 14

Which of the following is NOT a correct guideline for balancing chemical equations?

Accepted Answer

Change the subscripts to balance the equation.

Question 15

What is the correct sequence of steps for solving a mass-to-mass stoichiometry problem?

Accepted Answer

Convert mass of A to moles of A, use mole ratio to find moles of B, convert moles of B to mass of B.

Question 16

Which of the following best describes a single displacement reaction?

Accepted Answer

A reaction where an element replaces another element in a compound.

Question 17

What is the theoretical yield of $MgO$ when 13.1 g of $Mg$ reacts with excess $O_2$? (Molar mass $Mg = 24.31$ g/mol, $MgO = 40.30$ g/mol)

Accepted Answer

21.7 g

Question 18

Which of the following is the correct interpretation of the coefficients in a balanced chemical equation?

Accepted Answer

They represent the number of molecules or moles of each substance.

Question 19

In the reaction $2Na_3PO_4(aq) + 3CaCl_2(aq) \rightarrow Ca_3(PO_4)_2(s) + 6NaCl(aq)$, what volume (in mL) of 0.150 M $Na_3PO_4$ is needed to produce 1.35 g of $Ca_3(PO_4)_2$? (Molar mass $Ca_3(PO_4)_2 = 310.18$ g/mol)

Accepted Answer

19.4 mL

Chemical Reactions and Stoichiometry: Study Guide

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