Question

How many grams of solute are needed to make 37.5 mL of 0.750 M KI solution? Round to three significant digits.

Answer 1

4.648 gm of solute is needed to make 37.5 mL of 0.750 M KI solution.

Solution:  

We will start with the Molarity  

$\text { Molarity }=\text { Mole of solute } \div \text { liter of solution }$

Also we know 1000 ml = 1 L

Therefore 37.5 ml by 1000ml we obtained 0.0375L  

Equation for solving mole of solute

$\text { Mole of solute }=\text { Molarity } \times \text { Liters of solution }$

Now, multiply 0.750M by 0.0375

Substitute the known values in the above equation we get

$0.750 \times 0.0375=0.0281$

Also we know that Molar mass of KI is 166 g/mol

So divide the molar mass value to get the no of grams.

$0.028 \times 166=4.648$

So 4.648 gm of Solute is required for make 37.5 mL of 0.750 M KI solution.