1. You have a solution of 0.01962 M zinc(II) chloride. (a) How many moles of sol
ID: 898273 • Letter: 1
Question
1. You have a solution of 0.01962 M zinc(II) chloride. (a) How many moles of solute are contained in 45.73 mL of solution? (b) How many grams of solute are contained in 45.73 mL of solution? (c) What volume (in millilitres) of solution is needed to obtain 0.00140 moles of solute?
2. Sodium sulfide reacts with hydrochloric acid to produce hydrogen sulfide and sodium chloride. How many grams of sodium sulfide are required for complete reaction with 15.0 mL of 0.539 M hydrochloric acid? The molar mass of sodium sulfide is 78.046 g/mol. (Hint: start by writing the balanced equation for the reaction.)
Explanation / Answer
1. 0.01962 M zinc(II) chloride
a) No of moles of ZncL2 = (45.73/1000)*0.01962 = 0.000897 mole.
b) mass of ZnCl2 = 0.000897*mwt = 0.000897*136.315 = 0.122 grams
c) Volume of solute = n/M = 0.0014/0.01962 = 0.07135 L = 71.35 ml
2. Na2S + 2Hcl ----> 2NaCl + H2S
nO OF Moles of HcL = 15/1000*0.539 = 0.0081 mole.
From equation , 1 mole Na2S = 2 mole HcL
No of moles of Na2S = 0.0081/2 = 0.00405 mole.
mass of Na2S = 0.00405*78.046 = 0.3161 grams
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