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1) How many grams of NaCl are required to make 500.0 mL of a 1.500 M solution? -

ID: 910476 • Letter: 1

Question

1) How many grams of NaCl are required to make 500.0 mL of a 1.500 M solution?

-is it 43.83 g?

2) Consider the following balanced reaction. How many moles of O2 are formed when 58.6 g of KNO3 decomposes? MM KNO3 is 101.11g/mol.

4 KNO3(s) --> 2 K2O (s) + 2 N2(g) + 5 O2 (g)

3) Consider the following balanced reaction. How many liters of 0.260 M Na2S are needed to react with 0.04000 L of 0.315 M AgNO3?

Na2S (aq) + 2 AgNO3(aq) --> 2 NaNO3(aq) + Ag2S(s)

4) Consider the following balanced reaction. How many moles of Fe(OH)2 can form from 0.1750 L of 0.227 M LiOH solution?

F3Cl2(aq) + 2 LiOH(aq) --> Fe(OH)2(s) + 2 LiCl (aq)

Explanation / Answer

1)

moles of NaCl = 500 x 1.5 / 1000 = 0.75

moles = mass / molar mass

0.75 = mass / 58.5

mass of NaCl = 43.875 g

2)

4 KNO3(s)      ------------>    2 K2O (s) + 2 N2(g) + 5 O2 (g)

moles of KNO3 = 58.6g / 101.11

                          = 0.58

4 mol of KNO3 ---------------- give 5 mol of O2

0.58 mol of KNO3 --------------- ??

moles of O2 = 0.58 x 5 / 4 = 0.725

moles of O2 =0.725

3)

Na2S (aq) + 2 AgNO3(aq) ------------------> 2 NaNO3(aq) + Ag2S(s)

moles of AgNO3 = 0.04 x 0.315 = 0.0126

1 mol of Na2S need ----------------   2 mol of AgNO3

   ?? mol of Na2S             -------------   0.0126 mol AgNO3

moles of Na2S = 6.3 x 10^-3

moles = molarity x volume

0.0063 = 0.26 x volume

volume of Na2S = 0.02423 L

4)

FeCl2(aq) + 2 LiOH(aq) --> Fe(OH)2(s) + 2 LiCl (aq)

moles of LiOH = 0.1750 x 0.227 = 0.0397

2 mol LiOH forms ---------------- 1 mol Fe(OH)2

0.0397 mol LiOH --------------- ??

moles of Fe(OH)2 = 0.0397 / 2 = 0.01086

moles of Fe(OH)2 = 0.01086