Question

The first task you are assigned in your summer laboratory job is to prepare a concentrated NaOH stock solution. The molecular weight of NaOH is 40. How many grams of solid NaOH will you need to weigh out to obtain a 500 mL solution that has a concentration of 10 M

Answer 1

Answer:

200g of NaOH

Explanation:

The following data were obtained from the question:

Molar mass of NaOH = 40g/mol

Volume = 500mL

Molarity of NaOH = 10M

Next, we shall determine the number of mole of NaOH present in the solution. This is illustrated below:

Molarity of NaOH = 10M

Volume = 500mL = 500/1000 = 0.5L

Mole of NaOH =...?

Molarity = mole /Volume

10 = mole /0.5

Cross multiply

Mole = 10 x 0.5

Mole of NaOH = 5 moles

Finally, we can convert 5 moles of NaOH to grams. This is illustrated below:

Molar mass of NaOH = 40g/mol

Mole of NaOH = 5 moles

Mass of NaOH =...?

Mole = Mass /Molar Mass

5 = Mass /40

Cross multiply

Mass = 5 x 40

Mass of NaOH = 200g

Therefore, 200g of NaOH is needed to prepare the solution.