Question

What is the mass of 5.74 x 1021 formula units of sodium hydroxide: NaOH (Mw. 40.00 g/mol)?

Answer 1

0.38g

Explanation:

Given parameters:

Number of formula units = 5.74 x 10²¹

Molar mass of NaOH = 40g/mol

Unknown:

Mass of NaOH = ?

Solution:

The best way to solve this problem is the use the mole concept.

A mole is the amount of substance that contains the avogadro's number of particles.

The avogadro's number of particles is 6.02 x 10²³particles.

Particles = neutrons, protons, electrons, formula units, e.t.c

To solve this problem, find the the number of moles first then convert to mass.

 6.02 x 10²³  formula units =  1 moles

 5.74 x 10²¹ formula units = $\frac{5.74 x 10^{21} }{6.02 x 10^{23} }$ = 0.95 x 10$^{-2}$  moles

  Mass of NaOH = number of moles x molar mass = 0.0095 x 40  = 0.38g

learn more:

Molar mass brainly.com/question/2861244

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