Unit:1 moles

What is the molar mass of C8H18?

114.22 g/mol

Which compound has the largest molar mass: C8H18, CuCl2, or H2O?

C8H18

Which compound has the smallest molar mass: C8H18, CuCl2, or H2O?

H2O

What is the argument made by the student regarding the mass of NaCl and H2O2?

The student argues that because the measured mass of NaCl is greater than H2O2, there are more moles of NaCl.

Do you agree with the student's argument about moles of NaCl and H2O2? Why or why not?

Disagree; the number of moles is determined by dividing mass by molar mass.

What is the calculated number of moles in 4.08 g of H2?

2.02 moles.

What must you divide by to calculate the number of moles of a substance?

The molar mass of the substance.

What is the mass of one mole of a substance called?

Molar mass.

What unit is used to measure very large amounts of small particles?

Mole.

What is the mathematical formula for percent composition?

% of element = (mass of element / mass of compound) x 100.

Calculate the percent composition of carbon in CO2.

27.27%.

What is the empirical formula?

The simplest whole number ratio of each element in a compound.

What is a molecular formula?

The actual formula indicating the true number of atoms of each element.

What is the empirical formula for butene (C4H8)?

CH2.

How do you find the empirical formula from percent composition?

Convert percent to mass, then mass to moles, divide by the smallest number of moles.

What is the empirical formula for magnetite (iron oxide) found to be 72.4% Fe and 27.6% O?

Fe3O4.

What is the empirical formula for ibuprofen (C13H18O2) given its molecular molar mass is 206.31 g/mol?

C13H18O2.

What information do you use to determine how many times the empirical formula fits into the molecular formula?

Divide the molecular molar mass by the empirical formula molar mass.

What is the percentage of oxygen in carbon dioxide (CO2)?

72.73%.

If 40.0 g of carbon gives approximately how many moles of carbon?

3.33 moles.

Compare the empirical formula and molecular formula of compounds with the same empirical formula.

The empirical formula is simplified; the molecular formula is the actual counted formula.