How many grams of K2CO3 are needed to prepare a 400.0 mL of a 4.25M solution?

1.7 g

235 g

81.3 g

138 g

235 g

Explanation:

From the question;

Volume is 400.0 mL Molarity of a solution is 4.25 M

We need to determine the mass of the solute K₂CO₃,

we know that;

Molarity = Number of moles : Volume

Therefore;

First we determine the number of moles of the solute;

Moles = Molarity * volume

Moles of K₂CO₃ = 4.25 M * 0.4 L

= 1.7 moles

Secondly, we determine the mass of K₂CO₃,

We know that;

Mass = Moles * Molar mass

Molar mass of K₂CO₃, is 138.205 g/mol

Therefore;

Mass = 1.7 moles * 138.205 g/mol

= 234.9485 g

= 235 g

Thus, the mass of K₂CO₃ needed is 235 g