Question

Question 1.

a.) Glucose, CxHyOz, contains 40.00% carbon and 6.71% hydrogen. What is the empirical formula of glucose? If the molecular mass of glucose is 180.16, determine its molecular formula.

b.) A fluoride of tungsten WFx, contains 38.27% of F. What is the oxidation state of the tungsten in this compound?

c.) 5.00 g of solid calcium carbonate is thermally decomposed in the following reaction:

CaCO3(s) CaO (s) + CO2(g)

What mass of CaO is formed? This oxide reacts with water to give Ca(OH)2. Write a balanced equation for this process.

Answer 1

Ans 1

Part A

Let Mass of Glucose = 100 g

Mass of C = 40 g

Mass of H = 6.71 g

?Mass of O = 100 - 40 - 6.71 = 53.29 g

?Moles of C = mass of C/molecular weight of C

= 40g/12.011g/mol

= 3.33 mol

?Moles of H = mass of H/molecular weight of H

= 6.71g/1.00794g/mol

= 6.66 mol

?Moles of O = mass of O/molecular weight of O

= 53.29g/16g/mol

= 3.33 mol

Molar ratio

C:H:O = 3.33 : 6.66 : 3.33

divide by the LOWEST number

Molar ratio

C:H:O = 1 : 2 : 1

empirical formula = CH2O

molecular formula = n x empirical formula;

MF = n (EF)

molecular mass of glucose = 180.16

180.0 g/mol = n x (12.011 + 2 x 1.00794 + 16.00)g/mol

n = 6

Molecular formula = (CH2O)6

= C6H12O6