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Chemical equations Knowledge-Based Practice

Chemistry · The Mole & Stoichiometry · Chemistry · Chemical Reactions & Equations

5 Chemistry practice questions on Chemical equations. Questions that assess core concepts and understanding.

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Questions

  1. 1.

    When aqueous calcium hydroxide reacts with aqueous phosphoric acid, solid calcium phosphate and liquid water are formed. According to the balanced chemical equation, how many moles of water are produced for every 1 mole of calcium phosphate formed?

    • A) 2
    • B) 3
    • C) 6
    • D) 4
  2. 2.

    Which of the following represents the correctly balanced chemical equation for the complete combustion of liquid ethanol, C2H5OH\text{C}_2\text{H}_5\text{OH}, using the lowest whole-number coefficients?

    • A) 2C2H5OH(l)+7O2(g)→4CO2(g)+6H2O(g)2\text{C}_2\text{H}_5\text{OH(l)} + 7\text{O}_2\text{(g)} \rightarrow 4\text{CO}_2\text{(g)} + 6\text{H}_2\text{O(g)}
    • B) C2H5OH(l)+3O2(g)→2CO2(g)+3H2O(g)\text{C}_2\text{H}_5\text{OH(l)} + 3\text{O}_2\text{(g)} \rightarrow 2\text{CO}_2\text{(g)} + 3\text{H}_2\text{O(g)}
    • C) C2H5OH(l)+2O2(g)→2CO2(g)+3H2O(g)\text{C}_2\text{H}_5\text{OH(l)} + 2\text{O}_2\text{(g)} \rightarrow 2\text{CO}_2\text{(g)} + 3\text{H}_2\text{O(g)}
    • D) C2H5OH(l)+3O2(g)→2CO2(g)+2H2O(g)\text{C}_2\text{H}_5\text{OH(l)} + 3\text{O}_2\text{(g)} \rightarrow 2\text{CO}_2\text{(g)} + 2\text{H}_2\text{O(g)}
  3. 3.

    According to the fundamental principles governing balanced chemical equations, which of the following statements is always correct for a chemical reaction?

    • A) The total number of reactant molecules must equal the total number of product molecules.
    • B) The total mass of the reactants consumed equals the total mass of the products formed.
    • C) The sum of the stoichiometric coefficients on the reactant side must equal the sum on the product side.
    • D) The total number of moles of gaseous reactants must equal the total number of moles of gaseous products.
  4. 4.

    When the chemical equation Al(s)+H2SO4(aq)→Al2(SO4)3(aq)+H2(g)\text{Al(s)} + \text{H}_2\text{SO}_4\text{(aq)} \rightarrow \text{Al}_2(\text{SO}_4)_3\text{(aq)} + \text{H}_2\text{(g)} is balanced using the lowest whole-number coefficients, what is the sum of all the stoichiometric coefficients?

    • A) 8
    • B) 9
    • C) 10
    • D) 12
  5. 5.

    When the chemical equation NH3(g)+O2(g)→NO(g)+H2O(g)\text{NH}_3\text{(g)} + \text{O}_2\text{(g)} \rightarrow \text{NO(g)} + \text{H}_2\text{O(g)} is balanced using the smallest set of whole-number coefficients, what is the stoichiometric coefficient in front of O2(g)\text{O}_2\text{(g)}?

    • A) 2
    • B) 3
    • C) 4
    • D) 5

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