Topic 1 All - Stoichiometric Relationships

Which equation represents condensation?

• A. $\hspace{1em}$ $\ce{Br_2(l)\rightarrow Br_2(g)}$

• B. $\hspace{1em}$ $\ce{H2O\ \left(g\right)\rightarrow\ H2O\ (l)}$

• C. $\hspace{1em}$ $\ce{CO2(s)\rightarrow CO_2(g)}$

• D. $\hspace{1em}$ $\ce{ NaOH\left(aq\right) +\ HCl\ \left(aq\right)\rightarrow\ NaCl\left(aq\right) +\ H_2O(l)}$

Which of the following statements does not conform to the definition of a mole?

• A.$\hspace{1em}$ 1 mole is the number of H$_{2}$O molecules in 18.02 g of H$_{2}$O

• B.$\hspace{1em}$ 1 mole of Fe has a mass equal to the relative atomic mass of Fe in grams

• C.$\hspace{1em}$ 1 mole of any substance contains 6.02 $\times$ 10$^{23}$ particles

• D.$\hspace{1em}$ 1 mole is the number of H$_{2}$ molecules in 1.01 g of $\ce{H2}$

Which of the following is an example of a mixture?

• A.$\hspace{1em}$ Sucrose

• B.$\hspace{1em}$ Distilled water

• C.$\hspace{1em}$ Seawater

• D.$\hspace{1em}$ Sodium chloride

Which of the following statements is not a feature of Dalton's Atomic Theory?

• A.$\hspace{1em}$ Elements are made up of very small particles known as atoms.

• B.$\hspace{1em}$ All the atoms of an element are identical in mass but not in size.

• C.$\hspace{1em}$ Compounds are composed of atoms of more than one element.

• D.$\hspace{1em}$ During a chemical reaction, atoms are only rearranged, not created or destroyed.

Which of the following is a characteristic of liquids?

• A.$\hspace{1em}$ Their particles vibrate about fixed positions

• B.$\hspace{1em}$ They can be compressed easily

• C.$\hspace{1em}$ They take up the shape of the container they are in

• D.$\hspace{1em}$ The particles move freely and quickly in all directions

What name is given to a compound composed of two non-metals?

• A.$\hspace{1em}$ Polyatomic ionic

• B.$\hspace{1em}$ Ionic

• C.$\hspace{1em}$ Binary molecular

• D.$\hspace{1em}$ Alloy

What do you call the maximum amount of product that would result from the complete consumption of the limiting reagent?

• A.$\hspace{1em}$ Actual yield

• B.$\hspace{1em}$ Experimental yield

• C.$\hspace{1em}$ Percent yield

• D.$\hspace{1em}$ Theoretical yield

Which of the following methods is used to separate a solid from a liquid in a heterogeneous mixture?

• A.$\hspace{1em}$ Distillation

• B.$\hspace{1em}$ Filtration

• C.$\hspace{1em}$ Crystallisation

• D.$\hspace{1em}$ Sublimation

For a fixed mass of gas at a constant temperature, what happens to the volume if the pressure of the gas is doubled?

• A.$\hspace{1em}$Volume will remain the same

• B.$\hspace{1em}$Volume will double

• C.$\hspace{1em}$Volume will be halved

• D.$\hspace{1em}$Volume will increase exponentially

A liquid has a boiling point of $-185 ^\circ\mathrm{C}$. What is this temperature in Kelvin?

• A.$\hspace{1em}$ 88 K

• B.$\hspace{1em}$ $-88$ K

• C.$\hspace{1em}$ 458 K

• D.$\hspace{1em}$ $-458$ K

Which of the following conditions makes gases deviate from ideal behavior?

• A.$\hspace{1em}$ High pressure and high temperature

• B.$\hspace{1em}$ Low pressure and low temperature

• C.$\hspace{1em}$ High pressure and low temperature

• D.$\hspace{1em}$ Low pressure and high temperature

Which compound has the largest molar mass?

• A.$\hspace{1em}$ $\ce{FeSO4}$

• B.$\hspace{1em}$ $\ce{K2Cr2O7}$

• C.$\hspace{1em}$ $\ce{KMnO4}$

• D.$\hspace{1em}$ $\ce{(NH4)3PO4}$

Which of the following statements is true?

• A.$\hspace{1em}$ The empirical formula shows only the type of each atom in a molecule.

• B.$\hspace{1em}$ The molecular formula is always the same as the empirical formula.

• C.$\hspace{1em}$ Organic molecules often have different empirical and molecular formulas.

• D.$\hspace{1em}$ The empirical formula is always greater than the molecular formula.

Nitrogen gas reacts with hydrogen gas to produce ammonia as per the following chemical equation:

$\ce{N2(g) + 3H2(g) -> 2NH3(g)}$

If 0.86 $\textit{moles}$ of $\ce{N2}$ are mixed with 0.50 $\textit{moles}$ of $\ce{H2}$, which reactant is in excess?

• A.$\hspace{1em}$ $\ce{N_{2}}$

• B.$\hspace{1em}$ $\ce{H_{2}}$

• C.$\hspace{1em}$ $\ce{NH_{3}}$

• D.$\hspace{1em}$ Both reactants are in excess

Calculate the number of moles in $20.5$ grams of sodium phosphate ($\ce{Na3PO4}$).

• A.$\hspace{1em}$ 0.125 mol

• B.$\hspace{1em}$ 1.25 mol

• C.$\hspace{1em}$ 12.5 mol

• D.$\hspace{1em}$ 125 mol

Which of the following polyatomic ions formulas is incorrect?

• A.$\hspace{1em}$ $\ce{NO^-_3}$

• B.$\hspace{1em}$ $\ce{OH^-}$

• C.$\hspace{1em}$ $\ce{SO^{2-}_4}$

• D.$\hspace{1em}$ $\ce{CO^{2-}_4}$

Which of the following substances would have the lowest mass?

• A.$\hspace{1em}$ 2.50 $\textit{moles}\$ H$_2$O

• B.$\hspace{1em}$ 2.50 $\textit{moles}$ CH$_4$

• C.$\hspace{1em}$ 2.00 $\textit{moles}$ SO$_2$

• D.$\hspace{1em}$ 2.00 $\textit{moles}$ CO$_2$

Which of the following is incorrect?

What is the correct order of steps when performing titration?

• I.$\hspace{1em}$	Add the indicator to the flask
  II.$\hspace{1em}$	Prepare the standard solution
  III.$\hspace{1em}$	Swirl the flask while titrating
  IV.$\hspace{1em}$	Fill the burette with the titrant
  V.$\hspace{1em}$	Observe the endpoint

• A.$\hspace{1em}$IV, I, III, II, V

• B.$\hspace{1em}$IV, II, III, I, V

• C.$\hspace{1em}$II, IV, I, III, V

• D.$\hspace{1em}$II, IV, III, I, V

Bromine has 2 stable isotopes: bromine-79 and bromine-81. What is the relative atomic mass of bromine (Br)?

Isotope	Relative Abundance	Atomic Mass
$^{79}$Br	50.69%	78.92
$^{81}$Br	49.31%	80.92

• A.$\hspace{1em}$ 78.5

• B.$\hspace{1em}$ 80.1

• C.$\hspace{1em}$ 81.2

• D.$\hspace{1em}$ 79.9

Refer to the following chemical equation: $\ce{2NO2 (g) -> N2O4 (g)}$

At the same temperature and pressure, 25.0 $\textit cm^3$ of nitrogen dioxide ($\ce{NO2}$) gas is completely converted to dinitrogen tetroxide ($\ce{N2O4}$) gas. What will be the volume of $\ce{N2O4}$ produced?

• A.$\hspace{1em}$10.0 $\textit cm^3$

• B.$\hspace{1em}$12.5 $\textit cm^3$

• C.$\hspace{1em}$25.0 $\textit cm^3$

• D.$\hspace{1em}$50.0 $\textit cm^3$

How many molecules are there in 4.80 $\textit{moles}$ of glucose?

• A.$\hspace{1em}$ 2.89 $\times$ 10$^{24}$ molecules

• B.$\hspace{1em}$ 2.50 $\times$ 10$^{24}$ molecules

• C.$\hspace{1em}$ 3.50 $\times$ 10$^{24}$ molecules

• D.$\hspace{1em}$ 2.59 $\times$ 10$^{24}$ molecules

[Maximum mark: 4]

Ammonium perchlorate is an ionic compound ($\ce{NH4ClO4}$) that reacts with aluminium to make aluminium oxide
($\ce{Al_2O_3}$), aluminium chloride ($\ce{AlCl_3}$), nitrogen monoxide gas ($\ce{NO}$), and water at room temperature.

1. State the balanced chemical equation, including state symbols. [2]
   

2. Outline why a chemical equation must be balanced. [1]
   

3. Outline what you would expect to observe about the mass of the products compared to the mass of the reactants in this reaction. [1]
   

Based on the graph below, choose the correct statement that describes the relationship between pressure and temperature for a fixed mass and volume of a gas?

• A.$\hspace{1em}$Pressure is inversely proportional to the absolute temperature

• B.$\hspace{1em}$Pressure is directly proportional to the square of the absolute temperature

• C.$\hspace{1em}$Pressure is inversely proportional to the square of the absolute temperature

• D.$\hspace{1em}$Pressure is directly proportional to the absolute temperature

[Maximum mark: 5]

Eugenol is an oily, aromatic liquid extracted from essential oils such as clove and cinnamon. The molecular formula of eugenol is C$_{10}$H$_{12}$O$_{2}$.

1. Calculate the molar mass of eugenol. [1]
   

2. Determine the percentage by mass of carbon, hydrogen, and oxygen in eugenol. [3]
   

3. Predict the simplest, whole-number ratio of the atoms in eugenol. [1]
   

$14.01\,g$ of nitrogen gas ($\ce{N2}$) is reacted with excess $\ce{H2}$. What volume of ammonia ($\ce{NH3}$) gas would be produced at STP? The molar volume of a gas at STP is $22.7 \,dm^3$.

$\ce{N2(g) + 3H2(g) -> 2NH3(g)}$

• A.$\hspace{1em}$ $11.4\, dm^3$

• B.$\hspace{1em}$ $22.7\, dm^3$

• C.$\hspace{1em}$ $34.1\, dm^3$

• D.$\hspace{1em}$ $45.4\, dm^3$

What is the percentage by mass of S in the compound sulfur dioxide $\ce{SO2}$?

• A.$\hspace{1em}$ 25%

• B.$\hspace{1em}$ 50%

• C.$\hspace{1em}$ 75%

• D.$\hspace{1em}$ 100%

When a solution of lead (II) nitrate is mixed with a solution of potassium hydroxide, a precipitate containing lead (II) ions forms.

Which ions are considered to be the spectator ions?

• A. $\hspace{1em}$ Pb$^{2+}$, NO$_3^-$

• B. $\hspace{1em}$ K$^+$, OH$^-$

• C. $\hspace{1em}$ Pb$^{2+}$, OH$^-$

• D. $\hspace{1em}$ K$^+$, NO$_3^-$

When balanced, what is the sum of the coefficients for the equation below with the lowest whole-number ratio?

$\underline{\textrm{\htmlStyle{color: white;}{BL}}}$ $\ce{NO_2\left(g\right)}$ + $\underline{\textrm{\htmlStyle{color: white;}{BL}}}$ $\ce{H2O\left(l\right)\ \rightarrow}$ $\underline{\textrm{\htmlStyle{color: white;}{BL}}}$ $\ce{HNO3\ \left(aq\right)}$ + $\underline{\textrm{\htmlStyle{color: white;}{BL}}}$ $\ce{NO\ (g)}$

• A. $\hspace{1em}$ 4

• B. $\hspace{1em}$ 6

• C. $\hspace{1em}$ 7

• D. $\hspace{1em}$ 5

What is the sum of the coefficients when the equation is balanced with whole numbers?

$\ce{\underline{\hspace{1em}}\,C_3H_7OH(l) + \underline{\hspace{1em}}\,O_2(g) -> \underline{\hspace{1em}}\,CO_2(g) + \underline{\hspace{1em}}\,H_2O(l)}$

• A.$\hspace{1em}$ $12$

• B.$\hspace{1em}$ $13$

• C.$\hspace{1em}$ $24$

• D.$\hspace{1em}$ $25$

[Maximum mark: 6]

Ascorbic acid (C$_{6}$H$_{8}$O$_{6}$), or vitamin C, is a water-soluble vitamin that is essential for our immune system.

1. Calculate the number of moles in 2.50 $\textit{g}$ of ascorbic acid. [1]
   

2. Calculate the mass of 1.28 $\textit{moles}$ of ascorbic acid. [1]
   

3. Calculate the number of molecules in 50.0 $\textit{g}$ of ascorbic acid. [2]
   

4. Determine the number of moles of carbon in 225 $\textit{mg}$ of ascorbic acid [2]
   

[Maximum mark: 15]

A solution of an unknown hydrate of calcium chlorate (Ca(ClO$_3$)$_2$ $\cdotp$ n H$_2$O) is made by dissolving 4.164 $g$ in 150.0 cm$^3$ of water. The resulting solution of calcium chlorate has a concentration of 0.1142 $mol \ dm^{-3}$.

1. 1. Determine the number of moles and the mass of calcium chlorate present in the solution. [2]
      

   2. Determine the mass of water and then the number of moles of water that was present in the hydrate used to make the original solution. [2]
      

   3. Determine the value of n in the hydrate formula, Ca(ClO$_3$)$_2$ $\cdotp$ n H$_2$O. [1]
      

2. The calcium chlorate solution made above is then mixed with 200.0 $cm^3$ of $0.07500 \ mol \ dm^{-3}$ sodium phosphate (Na$_3$PO$_4$ ), producing a precipitate of calcium phosphate, Ca$_3$(PO$_4$)$_2$.

   1. Write the net ionic equation for this reaction, including state symbols. [2]
      

   2. Determine the limiting reactant in this reaction, showing your work. [2]
      

   3. If 1.535 $g$ of calcium phosphate is recovered, determine the percent yield in this reaction. [3]
      

   4. Determine the concentration of phosphate ions remaining in the solution after removing the precipitate, assuming that is the only loss of phosphate ions. [3]
      

[Maximum mark: 7]

The diagram below represents the heating of ice starting at $-20 ^\circ \mathrm{C}$.

1. Complete the table. [5]
   

   Segment number	What phase(s) is/are present?	What is happening at the particle level?	What phase change, if any, is taking place?
   1
   2
   3
   4
   5

2. Give the melting point of the substance. [1]
   

3. Identify the state of particles at $110^\circ\mathrm{C}$. [1]
   

[Maximum mark: 8]

The ideal gas equation is a formula that combines the relationship between pressure, volume, temperature, and the number of moles.

1. Complete the table below by calculating the missing variables of the ideal gas equation. [4]
   

$\mathbf{P}$	$\mathbf{V}$	$\mathbf{n}$	$\mathbf{T}$
(1)	$\quad 0.015\, m^{3}\quad$	$0.400\, mol$	$37 ^\circ \mathrm{C}$
$\quad 152,000\, Pa\quad$	(2)	$2.00\, mol$	$\quad 298.15\, K\quad$
$31,000\, Pa$	$0.25\, m^{3}$	(3)	$271.15\, K$
$250\,kPa$	$0.75\, dm^{3}$	$\quad 0.580\, mol\quad$	(4)

2. A $256\, cm^{3}$ flask contains $0.800\, g$ of a gaseous compound with an empirical formula of CHCl. The pressure and the temperature of the gas are respectively $10^{5}\, Pa$ and $373\, K$. Determine the molecular formula of the compound. [4]
   

[Maximum mark: 7]

Lipoic acid is an antioxidant that can be taken as a supplement for the body.

1. Determine the empirical formula of lipoic acid. [4]
   

Element	Percentage Composition by mass
C	46.56%
H	6.85%
O	15.5%
S	31.08%

2. Calculate the molar mass of the empirical formula of lipoic acid. [1]
   

3. If the actual molar mass of lipoic acid is 206.44 $\textit{g} \ mol^{-1}$, determine its molecular formula. [2]
   

[Maximum mark: 4]

Liquid butanol (C$_4$H$_9$OH) burns or combusts in oxygen to produce CO$_{2(g)}$ and H$_2$O${(g)}$.

1. Write a balanced equation, including state symbols, for this reaction. [1]
   

2. When 1.250 $cm^3$ of butanol is combusted in excess oxygen, 1.921 $dm^3$ of water vapor is collected at a pressure of 125.0 $kPa$ and 150.0$\degree$C. Calculate the moles of butanol that were combusted. [2]
   

3. Determine the density of liquid butanol in $g \ cm^{-3}$. [1]
   

[Maximum mark: 6]\

Chemical reactions can be classified into different types.

1. For each of the word equations below, identify the type of chemical reaction taking place. [3]
   

   1. Potassium chlorate decomposes to potassium chloride and oxygen gas.

   2. Zinc reacts with hydrochloric acid to produce zinc chloride and hydrogen gas.

   3. Ammonia combines with hydrogen chloride producing ammonium chloride.

2. In the table below, write the formulas of the products formed when double replacement reactions take place between the given reactants. [3]
   

• 	Reactants	$\quad$Products$\quad$
  (i)	$\ce{AgNO_3}$ and $\ce{KI}$
  (ii)	$\ce{HCl}$ and $\ce{Ba(OH)_2}$
  (iii)$\hspace{1em}$	$\quad\ce{Pb(NO_3)_2}$ and $\ce{K_2SO_4}\quad$

What is the molarity of a solution containing $7.45\, g$ of KCl dissolved in $250\, cm^3$ solution?

• A.$\hspace{1em}$ $0.10\, mol\, dm^{-3}$

• B.$\hspace{1em}$ $0.149\, mol\, dm^{-3}$

• C.$\hspace{1em}$ $0.40\, mol\, dm^{-3}$

• D.$\hspace{1em}$ $0.025\, mol\, dm^{-3}$