Question

1. how many grams are in 0.50 moles of sodium hydroxide (naoh)?

a. 20 g
b. 40 g
c. 10 g
d. 80 g

1. how many moles are in 18.0 g of water (h₂o)?

a. 0.50 mol
b. 1.00 mol
c. 2.00 mol
d. 18.0 mol

1. which conversion factor is needed to convert grams to moles?

a. avogadros number
b. liters at stp
c. molar mass
d. density

Explanation:

Question 17

Step1: Calculate molar mass of NaOH

Molar mass of Na = 23 g/mol, O = 16 g/mol, H = 1 g/mol.
$$M_{\text{NaOH}} = 23 + 16 + 1 = 40\ \text{g/mol}$$

Step2: Relate moles to mass

Use formula $m = n \times M$, where $n=0.50\ \text{mol}$, $M=40\ \text{g/mol}$.
$$m = 0.50 \times 40 = 20\ \text{g}$$

Step1: Calculate molar mass of H₂O

Molar mass of H = 1 g/mol, O = 16 g/mol.
$$M_{\text{H}_2\text{O}} = (2 \times 1) + 16 = 18\ \text{g/mol}$$

Step2: Relate mass to moles

Use formula $n = \frac{m}{M}$, where $m=18.0\ \text{g}$, $M=18\ \text{g/mol}$.
$$n = \frac{18.0}{18} = 1.00\ \text{mol}$$

To convert grams (mass) to moles, the relationship $n = \frac{m}{M}$ is used, where $M$ is molar mass. Avogadro's number converts moles to particles, STP volume relates to gas moles, and density relates mass to volume, so only molar mass works for gram-to-mole conversion.

Answer:

A. 20 g

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Question 18