Question

A student dissolves 24.2 g of NaCl in 500 mL of water. Another student dissolved 24.2 g of KI in 500 mL of water. Why do the two solutions have different molarities?

a)The volumes of the solutes differ.

b)The compounds have different molar masses.

c)The final volumes of solution are different.

d)The final solutions have different masses

Answer 1

c)The final volumes of solution are different.

Answer 2

Answer: b)The compounds have different molar masses.

Step-by-step explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.

`Molarity=(n* 1000)/(V_s)`

where,

n= moles of solute

`Moles=\frac{\text{Given mass}}{\text{Molar mass}}`

`V_s` = volume of solution in ml

Now put all the given values in the formula of molarity, we get

1. For
`NaCl`

`Molarity=(24.2* 1000)/(58.5* 500)=0.83mole/L`

Therefore, the molality of
`NaCl` solution will be 0.83 mole/L.

2. For
`KI`

`Molarity=(24.2* 1000)/(166* 500)=0.29mole/L`

Therefore, the molality of
`KI` solution will be 0.29 mole/L.