To enter a number in scientific notation, such as 1.5x10-4, use the following notation: 1.5*10^-4 (the * is above the 8 and the ^ is above the 6).

1) Determine the mass percent of iron in Fe3O4.

%

2) Hemoglobin is the protein that transports oxygen in mammals. Hemoglobin is 0.100 % Fe by mass, and each hemoglobin molecule contains four iron atoms. Calculate the molar mass of hemoglobin.

grams/mole

3) Carbon tetrachloride, CCl4, was formerly used as a dry cleaning agent. It is rather nasty stuff, in that it is easily absorbed through the skin and tends to do damage to your liver.

a) What is the mass (in grams) of one molecule of CCl4?

grams

b) How many moles of CCl4 are present in 20.1 g of the compound?

moles

c) How many molecules of CCl4 are present in 20.1 g of the compound?

molecules

d) How many chlorine atoms are present in 20.1 g of CCl4?

atoms of Cl

e) What is the mass percent of Cl in CCl4?

% of Cl