Question

1. The relation between gram and amu is represented by ____________________________(use NA = 6 x 10*23)

2. The atomic mass of Rubidium is 85, so the mass of one mole of Rubidium is______________________.

3. The atomic mass of silver (Ag) is 108. find the mass of two moles of silver atoms.___________________

4. The atomic mass of lithium (Li) is 7. the mass of one atom of lithium is ________________________.

5. Given the following atomic masses: N=14; O=16. tha is the molecular mass of N2O5?_______________________________

6. (Given: atomic masses of H=1; O =16;and S=32) The mass of one mole of sulphuric acid, H2SO4, is______________________________

7. Given the following atomic masses; N=14; O=16. What is the molar mass of N2O2?__________________________________________

8. How many moles are there in 3.9g of K? [Atomic mass of K=39]________________________________

9. Find the number of moles in 51 g of ammonia gas (NH3). [N=14; H=1]________________________

10. How many moles are present in 6.3 g of nitric acid HNO3? [Given atomic mass of H=1, N=14 and Q=16]

11. How many moles are contained in 620g of pure H2CO3? [Given atomic masses: H=1,C=12 and O=16]________________________

Answer 1

1. 1 gram= 6.022*10²³ amu

2. mass of 1 mole rubidium= 85.4678 grams

3.mass of two mole of Ag= 216 g

4.moles= mass/atomic mass, so 1= mass/7

= mass= 7g

5. N₂O₅ molecular mass= 2*14+5*16= 108 g/mol

6. mass of one mole of H₂SO₄ = 2*1+32 +4*16 = 98 g

7.molar mass of N₂O₂ = 2*14+2*16 = 60 g/mol

8. moles= weight/ molecualr weight

= 3.9/39= 0.1 moles

9. NH3 molecular weight= 14+3*1.008= 17.031 g/mol

number of moles= wt/mw = 51/ 17.031= 3 moles

10. moelcular weight of HNO3 = 63.01 g/mol

number of moles = 6.3/63.01= 0.1 moles

11. H2CO3 molecular weight = 62.03 g/mol ( 2*1+12+3*16=62.03)

number of mole s= 620/62.03 = 10 moles