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32 votes
32 votes
How many grams of NaOH are needed to make a 250.0 mL or a 4.2 M NaOH solution?

Group of answer choices

A. 1.05 grams NaOH

B. 42,000 grams NaOH

C. 42 grams NaOH

D. 1050 grams NaOH

User Boisterouslobster
by
2.4k points

1 Answer

20 votes
20 votes

Answer:

C.) 42 grams NaOH

Step-by-step explanation:

To find the mass of NaOH, you need to (1) find the moles (using the molarity equation) and then (2) convert moles to grams (using the molar mass).

(Step 1)

250.0 mL / 1,000 = 0.2500 L

Molarity = moles / volume (L)

4.2 M = moles / 0.2500 L

1.05 = moles

(Step 2)

Molar Mass (NaOH): 22.990 g/mol + 15.998 g/mol + 1.008 g/mol

Molar Mass (NaOH): 39.996 g/mol

1.05 moles NaOH 39.996 g
----------------------------- x ------------------ = 42 grams NaOH
1 mole

User SamJackSon
by
3.1k points