Chemistry abt atom and molecules and mole concept

Question

A calcium is 3.33 times the mass of a carbon atom. What is the atomic mass of calcium ?

A. 33

B.40

C.38

D.12

A 2.20 m solution contains 265 g of solvent. What is the molality of the solution after dillution with an additional 135g of solvent

A.1.46

B.4.32

C.6.10

D.5.50

Answer 1

Atomic mass of carbon is 12.001 so if calcium is 3.33 times this, it would be 3.33 x 12.001 = 39.96 = 40 Answer B

2.20 m solution means 2.20 moles of solute per kg of solvent. The original solution thus of 2.2 m would contain 2.20 moles/kg x 0.265 kg = 0.583 moles of solute. After adding 135 g (0.135 kg) of solvent, the total solvent = 0.265 kg + 0.135 kg = 0.4 kg. Final molality = 0.583 moles/0.4 kg = 1.4575 m = 1.46 m Answer A