Question

Sodium hydroxide, NaOH is a strong base that is used in industrial synthesis and process such as making paper.

What is the mass 2.60x10^22 molecules of NaOH(molar mass=40.0g/mol)?
Express the mass in grans to three significant figures

Answer 1

Avagadros number/ constant states that there are 6.022 x 10²³ units making up 1 mol of any substance.
In NaOH - there are 6.022 x 10²³ NaOH molecules in 1 mol of NaOH
Mass of 1 mol of NaOH - 40 g
therefore 6.022 x 10²³ molecules weigh - 40 g
Then 2.60 x 10²² molecules - 40 x 2.60 x 10²² / (6.022 x 10²³ )
mass is then - 1.73 g