WAEC WASSCE Stoichiometry of Chemical Reactions — practice questions
100 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice WAEC WASSCE Stoichiometry of Chemical Reactions in the app →In a chemical equation, where are the formulas of the reactants placed?What are the substances generated by a chemical reaction called, and where do they appear?In a balanced chemical equation, what is done with a coefficient of 1?Methane burns as CH4 + 2O2 giving CO2 + 2H2O. Which set of molecule numbers also satisfies this equation?Why may the subscripts in a formula not be altered when balancing an equation?Which smallest whole-number coefficients balance N2 + O2 giving dinitrogen pentoxide, N2O5?Ammonium nitrate decomposes to nitrogen, oxygen and water. Which balanced equation is correct?Balancing C2H6 + O2 first gives 3H2O and 2CO2, which needs seven oxygen atoms. Which O2 coefficient is used beAfter balancing ethane combustion with a fractional O2 coefficient, how is the conventional integer equation oThe equation 3N2 + 9H2 giving 6NH3 is balanced. Why is it not the preferred form?In a chemical equation, what does the abbreviation aq written after a formula indicate?What does an uppercase Greek delta written over a reaction arrow show?What distinguishes a molecular equation from a complete ionic equation?Which equation type shows every dissolved ionic reactant and product as its separate ions?Aqueous CaCl2 and AgNO3 react to give solid AgCl. Which ions are the spectator ions?What is a spectator ion?Mixing solutions of CaCl2 and AgNO3 gives solid AgCl. What does the net ionic equation state?Carbon dioxide dissolved in aqueous sodium hydroxide gives aqueous sodium carbonate and water. Which ion is thElectrolysis of brine turns NaCl and water into NaOH, H2 and Cl2. Which balanced molecular equation is correctWhich law makes it necessary for a chemical equation to be balanced?What defines a precipitation reaction?Precipitation reactions between two ionic compounds in solution are also known by which name?How is the solubility of a substance defined?A solid appears when the concentration of a substance in solution rises past a certain point. What point is thWhich group of cations forms soluble compounds with no exceptions listed in the solubility guidelines?Chloride, bromide and iodide salts are generally soluble. Which cations are the listed exceptions?Sulfate salts are generally soluble. Which of these sulfates is an exception and therefore insoluble?Carbonate, chromate, phosphate and sulfide compounds are generally insoluble. What is the listed exception?Hydroxide compounds are generally insoluble. Which cations are the stated exceptions?Solutions of potassium iodide and lead nitrate are mixed. Which net ionic equation describes what happens?Silver nitrate solution is mixed with sodium fluoride solution. What is predicted, and why?Which solution would precipitate barium ions from a water sample, and what solid forms?What is transferred between species during an acid-base reaction?In aqueous solution, what does an acid produce?Which compound is listed among the common strong acids?About what fraction of acetic acid molecules are in the ionized form in water under typical conditions?What is a base in aqueous solution?Why are NaOH, KOH and Ba(OH)2 all classified as strong bases?Ammonia dissolved in water gives NH4+ and OH- ions. How is ammonia classified, and why?What are the usual products of a neutralization reaction?Barium hydroxide solution is neutralized by nitric acid. Which balanced equation is correct?What is the net ionic equation for neutralizing any strong acid with an ionic hydroxide?In terms of electrons, what happens to a species that is oxidized?What happens to a species that is reduced?A reducing agent brings about the reduction of another substance. What happens to the reducing agent itself?How is the oxidation number of an element in a compound defined?What is the oxidation number of an atom in an elemental substance such as O2, Na or Cl2?Which rule governs the oxidation number of hydrogen in compounds?Which statement about the oxidation number of oxygen follows the assignment guidelines?What is the oxidation number of sulfur in H2S?What is the oxidation number of sulfur in the sulfite ion, SO3 2-?What is the oxidation number of sulfur in Na2SO4?What is the oxidation number of nitrogen in KNO3?What is the oxidation number of nitrogen in the ammonium ion, NH4+?What is the oxidation number of aluminium in AlH3?Which change identifies a reaction as an oxidation-reduction reaction?How is a combustion reaction described?What happens in a single-displacement reaction?Copper wire is placed in silver nitrate solution and the solution turns blue. What causes the blue colour?Is ZnCO3(s) giving ZnO(s) and CO2(g) a redox reaction?In 2H2O2(aq) giving 2H2O(l) and O2(g), one element is both oxidized and reduced. What is this type of reactionIn C2H4(g) + 3O2(g) giving 2CO2(g) + 2H2O(l), what happens to carbon?In the half-reaction method, how are oxygen atoms balanced?In the half-reaction method, what is added to balance the charge of a half-reaction?Dichromate ion oxidizes iron(II) in acid to give iron(III) and chromium(III). Which balanced equation is correFollowing the reporting convention, how are a 2+ charge and a plus two oxidation number written?What does the stoichiometry of a reaction describe?What is a stoichiometric factor?A recipe uses 1 cup mix, three quarters of a cup of milk and one egg for eight pancakes. How many eggs give 24For 2Al + 3I2 giving 2AlI3, how many moles of I2 react with 0.429 mol of Al?For 3Ca(OH)2 + 2H3PO4 giving Ca3(PO4)2 + 6H2O, how many moles of Ca(OH)2 react with 1.36 mol of H3PO4?For C3H8 + 5O2 giving 3CO2 + 4H2O, how many moles of CO2 form when 0.75 mol of propane burns?For (NH4)2SO4 + Ca(OH)2 giving 2NH3 + CaSO4 + 2H2O, how many moles of NH3 come from 4.0 mol of Ca(OH)2?Gallium metal of mass 29.0 g reacts as 4Ga + 3O2 giving 2Ga2O3. What mass of Ga2O3 can be prepared?What mass of CO reacts with 25.13 g of Fe2O3 according to Fe2O3 + 3CO giving 2Fe + 3CO2?Why does a mass-to-mass stoichiometry problem need more steps than a mole-to-mole one?What is a limiting reactant?A sandwich needs 2 slices of bread and 1 slice of cheese. With 28 slices of bread and 11 of cheese, what resulCombining 3 mol of H2 with 2 mol of Cl2 for H2 + Cl2 giving 2HCl, which reactant limits the product?When each reactant amount is used to work out how much product it would give, which reactant is the limiting oFor 3Si + 2N2 giving Si3N4, which reactant limits when 2.00 g of Si (28.09 g/mol) and 1.50 g of N2 (28.02 g/moHow do theoretical yield and actual yield differ?How is the percent yield of a reaction calculated?Reacting 1.274 g of CuSO4 with excess zinc gives 0.392 g of copper, against a theoretical 0.5072 g. What is thA student isolated 25 g of a compound from a procedure that should theoretically yield 81 g. What is the perceReacting 3.0 mol of H2 with 2.0 mol of I2 gave 1.0 mol of HI. What is the percent yield for H2 + I2 giving 2HIFor 2Cr + 2H3PO4 giving 2CrPO4 + 3H2, which is limiting when 0.50 mol Cr meets 0.75 mol H3PO4?How is the atom economy of a synthesis defined?What is quantitative analysis?In a titration, what is the difference between the titrant and the analyte?What is a buret used for in titration analysis?How do the equivalence point and the end point of a titration differ?Why are indicators added to the sample solution in many titrations?A 50.00 mL sample of HCl needs 35.23 mL of 0.250 M NaOH to reach the end point. What is the HCl molarity?A 20.00 mL oxalic acid sample needs 23.24 mL of 0.09113 M KMnO4, reacting as 2MnO4- with 5H2C2O4. What is the What defines a gravimetric analysis?Drying a sample by controlled heating to find its water content is an example of which method?A 0.4550 g mixture treated with excess Ba(NO3)2 gives 0.6168 g of BaSO4 (233.43 g/mol). What is the mass perceBurning 0.00126 g of polyethylene gives 0.00394 g CO2 (44.01 g/mol) and 0.00161 g H2O (18.02 g/mol). What is iIn the old vinegar test, potassium carbonate was added until bubbling stopped. What gas caused the bubbling?