Question

The concentration of KBr in a solution prepared by dissolving 2.21g of KBr in 897 g of water is __________ m.
A) 2.46.
B) 0.0167.
C) 2.07 x 10-5.
D) 0.0186.
E) 0.0207.

Answer 1

Answer:

E) 0.0207

Explanation:

The molal concentration, m, is defined as the ratio between moles of solute (In this case, KBr) per kg of solvent (water):

Moles KBr -Molar mass: 119g/mol-

2.21g KBr * (1mol / 119g) = 0.01857moles

Mass solvent:

897g * (1kg / 1000g) = 0.897kg

Molal concentration:

0.01857 moles / 0.897kg =

0.0207m

Right solution is:

E) 0.0207.