Question

3) Calculate the mass of 0.750 mole of C2H6O.

4) How many formula units are there in 5.4 g of NaCl?
5) How many moles are there in 50.0 g of CaCO3?

Answer 1

(3) 34.5grammes of C2H6O

(4) 5.56 x 10^22 Formula units

(5) 0.5 moles of CaCO3

Step-by-step explanation:

(3) molar mass of C2H6O = 24 + 6 + 16 = 46 g/mol

mass of C2H6O =0.75 mole x 46 g/mole = 34.5 grammes

(4) Formula units of NaCl = (5.4/ 58.5) x 6.022x10^23 = 5.56 x 10^22

(4) moles = mass / molar mass

molar mass of CaCO3 = 40 + 12 + 48 = 100 g/mol

moles of CaCO3 = 50/100 = 0.5 moles