Question

Please help me, tomorrow will be test

1.A chemical technician needs 3 L of 0.125 mol/L sodium hydroxide
solution. What mass of solid sodium hydroxide must be measured?

Answer 1

Answer:NaOH

Molarity= no. Of moles(n) ÷ vol.(litre)

♡n=given mass÷ molar mass

= w ÷40(it is molarmass ofNaOH)

♡ molarity =0.125

♡vol=3 litre

☆from above formula

# 0.125 = w ÷40× 3

w = 0.125 ×40 × 3

=15

Answer 2

Explanation:

Molecular weight of NaOH is 40 g/mol (truly sad that I know MW if NaOH is 40 without looking it up). To get .125 M, you multiply 40 g/mol * .125 mol/L = 5 g/L.

So you dissolve 5 g of NaOH in 1 L of water. Since you need 3 liter, you multiply by 3 to get 15 g to dissolve in 3 L of water.