exercise 30 sept2009

Exercise : Chemical formula and equation

Answer all the question given below.

1. Determine the relative molecular mass ( or relative formula mass) of each of the following
compounds:
(a) H2SO4 (b) Cu(NO3)2
(c) CoCl2.6H2O (d) glucose, C6H12O6
( Relative atomic mass : H;1 , C;12 , N;14 , O;16, S;32, Cl;35.5, Co;59, Cu;64 )

2. Calculate the number of particles in
(a) 12.8 g copper,Cu
(b) 1.2 mole of chloride ions,Cl-
( NA = 6.02 x 1023 particles)

3. Calculate the number of atoms in
(a) 0.125 mole of methane gas,CH4
(b) 36 g of glucose, C6H12O6

4. Determine the mass for each of the following substances:
(a) 1.25 mole of helium gas
(b) 2/5 mole of cobalt,Co
( Relative atomic mass He;4 , Co;59 )

5. Calculate the mass of following substances:
(a) 1.2 x 1022 zinc atoms
(b) 3 x 1023 ethanol (C2H5OH) molecules
( C;12, H;1 , O;16, Zn;65, NA= 6.02 x 1023 )

7. Calculate the number of moles of 672 cm3 of carbon dioxide gas at s.t.p
( 1 mol gas occupies 22.4 dm3 at stp)

8. Calculate the volume occupied by 1.4 g of ethane gas,C2H4 at room temperature and pressure.
( 1 mol gas occupies a volume of 24 dm3 at room temperature)

9. Cocaine,C17H21O4 is a drug .Calculate the number of cocaine molecules present in 6.06 g of the drug
( Relative atomic mass: H;1, C;12, N;14, O;16 , Na ;14 , NA= 6.02 x 1023 )

10. Caffein contains 49.5% carbon,5.2% hydrogen,28.9% nitrogen and 16.4% oxygen by weight.
Determine the empirical formula of caffeine.
( relative atomic mass H;1, C;12, N;14 , O;16 )