Chemistry : Stoichiometry-2


Q.1: What is a mole?

Q.2: What is the empirical formula of a compound ?

Q.3: What is the molar mass of a substance?

Q.4: What is a limiting reactant?

Q.5: A sample equal to the atomic mass of the element in gm contains -------- atoms.

Q.6: The molar mass of a compound can be obtained by -------- the atomic weights of the component atoms.

Q.7: Sodium hydroxide absorbs carbon dioxide as the following reaction suggests:
NaOH (aq) + CO 2 = Na 2 CO 3 (aq) + H 2 O (l)
Calculate the number of grams of carbon dioxide that can be absorbed by complete reaction with a solution that contains 5.00 gm of sodium hydroxide.

Q.8: Magnesium ribbon burns in oxygen as follows:
2Mg (s) + O2 (g) = 2MgO (s)
How many grams of MgO (s) are produced by complete reaction of 1.25 gm of magnesium ribbon?

Q.9: Sodium reacts with ammonia as follows:
NH3 (g) + Na (s) = NaNH 2 (s) + H 2 (g)
Balance the reaction. If 50.0 gm of each reactant is taken, suggest the limiting reactant and the amount of sodium amide formed.

Q.10: Powdered iron metal reacts with chlorine gas as folloes:
Fe (s) + Cl 2 (g) = FeCl 3 (s)
Balance the reaction. If 5.0 gm of iron powder is added to 10.0 gm of chlorine gas, suggest the limiting reactant and the amount of the product formed.

Q.11: Silicon carbide is manufactured by heating sand with carbon in a furnace. The reaction is :
SiO 2 (s) + C (s) = CO (g) + SiC (s)
What mass of silicon carbide would result if 1.0 kg of pure sand is heated with excess of carbon?

Q.12: Calcium chloride is produced by treating calcium carbonate with hydrochloric acid gas. The reaction is
CaCO 3 (s) + 2HCl (g) = CaCl >sub>2 (s) + CO 2 (g) + H 2 O (g)What is the percent yield if 155 gm of calcium carbonate is treated with 250.0 gm of anhydrous hydrochloric acid and only 142.0 gm of calcium chloride is obtained?

Q.13: Potassium chromate is added to precipitate lead ion quantitatively from its solution.
If 15 mg of lead ion is present in solution, what amount of potassium chromate should be added to guarantee precipitation of all lead ion in solution?

Q.14: Phosphorus reacts with chlorine gas as follows:
2P (s) + 3Cl 2 (g) = 2PCl 3 (l)
How many moles of the product would be produced if 1.00 gm of phosphorus is used with excess of chlorine gas?

Q.15: Calculate the mass percent of ammonium nitrate when 1.0 gm of ammonium is present in 10 gm of water.

Q.16: For a 15.0 % (by mass) sodium chloride solution, calculate the mass of sodium chloride in 150 gm of solution.

Q.17: For a 15 % (by mass) ammonium nitrate solution, calculate the amount of solution needed to obtain 35.0 gm of ammonium nitrate.

Q.18: A certain alloy is made by dissolving 5.31 gm of copper and 4.03 gm of zinc in 145 gm of iron. Calculate the percent of zinc in the alloy.

Q.19: A 151 gm portion of sodium chloride solution is evaporated, producing 5.35 gm of dry sodium chloride. Calculate the percentage of sodium chloride in the original solution.

Q.20: How many grams of potassium bromide are present in 125 gm of of 6.25 % (by mass) potassium bromide solution ?

Q.21: A hexane solution contains 5.2 % ( by mass) heptane and 2.9 % ( by mass ) pentane. Calculate the mass of heptane in 93 gm of the solution.

Q.22: If 52.0 gm of potassium carbonate are dissolved in 518 gm of water, the molality of the resulting solution will be ---------- .

Q.23: The mole fraction of alcohol in a solution of 2.00 moles of ethanol and 8.00 moles of water will be ---------- .

Q.24: The mass percent of 142 gm of hydrogen peroxide in 331 gm of water is --------- .

Q.25: Calculate the molarity of the solution containing 4.25 gm of copper chloride in 125 mL of the solution.

Q.26: If 275 gm of copper sulphate is dissolved in enough water to make 4.25 L, what is the molarity of the solution ?

Q.27: If 495 gm of sodium hydroxide is dissolved to a final volume of 20.0 L , what is the molarity of the solution?

Q.28 What volume of 0.25 M sodium chloride solution can be prepared from 5.2 gm of sodium chloride?

Q.29 Calculate the new molarity that results when 250. mL of water is added to 125. mL of 0.251 M hydrochloric acid.

Q.30 If 75 mL of 0.211 M sodium hydroxide is diluted to a volume of 125 mL, what is the concentration of sodium hydroxide in the diluted solution ?

Q.31: What volume of 0.175 M HCl solution is required to exactly neutralize 24.9 mL of 0.451 M NaOH solution ?

Q.32: Calculate the normality of 0.101 M Ba(OH) 2 solution.

Q.33: How many Liters of 0.103 M sulphuric acid are required to neutralize exactly 4.25 L of 0.104 M sodium hydroxide ?

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