Question

3.) how many moles are present in 10.0 grams of sodium hydroxide (naoh)? (1 point)
4 moles
2 moles
0.25 moles
0.5 moles
4.) the molar mass of sodium is 22.99 g/mol and the molar mass of chlorine is 35.45 g/mol. what is the mass in grams of 1.50 moles of sodium chlorine (nacl)?
your answer should be rounded to three significant figures.
(1 point)
87.66 g
0.0257 g
87.7 g
0.02567 g

Explanation:

Step1: Calculate molar mass of NaOH

The molar mass of Na ($22.99$ g/mol), O ($16.00$ g/mol), H ($1.01$ g/mol). Molar mass of NaOH = $22.99+16.00 + 1.01=40.00$ g/mol.

Step2: Calculate moles of NaOH

Use the formula $n=\frac{m}{M}$, where $m = 10.0$ g and $M = 40.00$ g/mol. So $n=\frac{10.0}{40.00}=0.25$ mol.

Step3: Calculate molar mass of NaCl

Molar mass of NaCl = molar mass of Na + molar mass of Cl = $22.99+35.45 = 58.44$ g/mol.

Step4: Calculate mass of 1.50 moles of NaCl

Use the formula $m=n\times M$, where $n = 1.50$ mol and $M = 58.44$ g/mol. So $m=1.50\times58.44 = 87.66$ g, rounded to three - significant figures is $87.7$ g.

Answer:

1. C. 0.25 moles
2. C. 87.7 g