Question 1

A sample of hydrated magnesium sulfate ($\mathrm{MgSO_4 \cdot xH_2O}$) weighing 5.00 g is heated to drive off all water, leaving 2.44 g of anhydrous $\mathrm{MgSO_4}$. What is the value of $x$ in the hydrate? (Molar masses: $\mathrm{MgSO_4}$ = 120.4 g/mol, $\mathrm{H_2O}$ = 18.0 g/mol)

Accepted Answer

$x = 5$

Question 2

Which of the following best describes the electron geometry and approximate bond angle of $\mathrm{NH_3}$?

Accepted Answer

Tetrahedral, $109.5^\circ$

Question 3

A student mixes solutions of $\mathrm{Na_2SO_4}$ and $\mathrm{Ba(NO_3)_2}$. What precipitate, if any, will form? Use solubility rules.

Accepted Answer

$\mathrm{BaSO_4}$

Question 4

Which of the following is the correct empirical formula for a compound containing 40.0% magnesium and 60.0% oxygen by mass?

Accepted Answer

$\mathrm{MgO}$

Question 5

Which molecule has a linear molecular geometry and a bond angle of $180^\circ$?

Accepted Answer

$\mathrm{CO_2}$

Question 6

A reaction between 10.0 g of $\mathrm{Al}$ and 35.0 g of $\mathrm{Cl_2}$ produces $\mathrm{AlCl_3}$ according to the equation: $2\mathrm{Al} + 3\mathrm{Cl_2} \rightarrow 2\mathrm{AlCl_3}$. What is the limiting reactant?

Accepted Answer

$\mathrm{Cl_2}$

Question 7

Which of the following ions forms a compound that is generally insoluble in water, except when paired with $\mathrm{Na^+}$, $\mathrm{K^+}$, or $\mathrm{NH_4^+}$?

Accepted Answer

$\mathrm{CO_3^{2-}}$

Question 8

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

Accepted Answer

A reaction in which two compounds exchange ions to form two new compounds

Question 9

What is the molecular geometry of $\mathrm{SF_4}$?

Accepted Answer

Seesaw

Question 10

A solution contains $\mathrm{Ag^+}$ and $\mathrm{Cl^-}$ ions. What will happen when these ions are mixed in water?

Accepted Answer

$\mathrm{AgCl}$ will precipitate

Question 11

Which of the following statements about limiting reactants is correct?

Accepted Answer

The limiting reactant is completely consumed first in a chemical reaction

Question 12

Which of the following compounds is always soluble in water?

Accepted Answer

$\mathrm{NaNO_3}$

Question 13

What is the percent yield if 12.0 g of $\mathrm{CuSO_4}$ is produced, but the theoretical yield is 15.0 g?

Accepted Answer

$80.0\%$

Question 14

Which of the following best describes the Lewis structure of $\mathrm{CO_2}$?

Accepted Answer

Central carbon atom with two double bonds to oxygen atoms

Question 15

Which of the following is the correct formula for a compound formed between $\mathrm{Al^{3+}}$ and $\mathrm{SO_4^{2-}}$?

Accepted Answer

$\mathrm{Al_2(SO_4)_3}$

Question 16

Which of the following is NOT a step in drawing a Lewis structure for a molecule?

Accepted Answer

Ignore the octet rule for second-period elements

Question 17

A student is asked to write the net ionic equation for the reaction between $\mathrm{Na_2CO_3}$ and $\mathrm{CaCl_2}$ in water. Which of the following is the correct net ionic equation?

Accepted Answer

$\mathrm{Ca^{2+}} + \mathrm{CO_3^{2-}} \rightarrow \mathrm{CaCO_3(s)}$

Question 18

Which of the following best explains why $\mathrm{H_2O}$ has a bent molecular geometry?

Accepted Answer

The oxygen atom has two lone pairs, causing repulsion and bending the molecule

Question 19

Which of the following is the correct electron geometry for $\mathrm{PCl_5}$?

Accepted Answer

Trigonal bipyramidal

General Chemistry II: Exam #2 Study Guide – CHEM116

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