1. What is the mass of potassium in a sample of KClO 4 that contains 5.67 g of o

ID: 1022778 • Letter: 1

Question

1. What is the mass of potassium in a sample of KClO4 that contains 5.67 g of oxygen? ______ g K

2. The compound X3Y is 65.6% X. What is the molar mass of Y if the molar mass of X is 71.8 g/mol? _______ g/mol

3. What is the formula of a compound if a sample of the compound contains 0.214 mol X, 0.268 mol Y, and 0.107 mol Z?

See instructions for writing formulas in the Instructions box of the assignment.

4. What is the simplest formula of a rhenium oxide that is 85.33 % Re by mass? Write the symbol of the metal first.

5. What is the empirical formula of a compound that is 39.81% Cu, 20.09% S, and 40.10% O? Write the elements in the order Cu, S, and O.

no of moles of oxygen = W/G.A.Wt

= 5.67/16 = 0.354moles

1 mole of KClO4 contains 4 moles of oxygen

4 moles of oxygen present in 1mole KClO4

0.354 moles of oxygen present in = 0.354/4 = 0.0885 moles of KClO4

There is 1 : 1 ratio of K and KClO4

no of moles of K = 0.0885 moles

mass of K = no of moles * gram atomic mass

= 0.0885*39 = 3.45g >>>>> answer

2. percentage of Y = 100-65.6 = 34.4%

0.0344 =

3. X Y Z

0.214 0.268 0.107

0.214/0.107 0.268/0.107 0.107/0.107

2 2.5 1

2*2 2.5*2 1*2

4 5 2

Empirical formula = X4Y5O2

4. o% = 100-85.33 = 14.67%

Element % A.Wt Relative number simple ratio

Re 85.33 186 85.33/186 =0.456 0.456/0.456 = 1

O 14.67 16 14.67/16 = 0.92 0.92/0.456 = 2

Empirical formula = ReO2

5 . Element % A.Wt Relative number simple ratio

Cu 39.81 63.5 39.81/63.5 = 0.627 0.627/0.627 = 1

S 20.09 32 20.09/32 = 0.627 0.627/0.627 = 1

O 40.1 16 40.1/16 = 2.5 2.5/0.627 = 4

Empirical formula = CuSO4

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