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What is the molarity of a solution prepared by dissolving [tex][tex]$12.0 g$[/tex][/tex] of sodium hydrogen carbonate, [tex][tex]$NaHCO _3$[/tex][/tex], in water to make [tex][tex]$250.0 mL$[/tex][/tex] of solution?

A. [tex][tex]$0.914 M$[/tex][/tex]
B. [tex][tex]$1.19 \times 10^{-2} M$[/tex][/tex]
C. [tex][tex]$0.571 M$[/tex][/tex]
D. [tex][tex]$2.28 M$[/tex][/tex]
E. [tex][tex]$0.143 M$[/tex][/tex]


Sagot :

To find the molarity of the solution, we will follow these steps in detail:

1. Determine the molar mass of sodium hydrogen carbonate ([tex]\(NaHCO_3\)[/tex]):
- Sodium (Na): [tex]\( 22.99 \, \text{g/mol} \)[/tex]
- Hydrogen (H): [tex]\( 1.01 \, \text{g/mol} \)[/tex]
- Carbon (C): [tex]\( 12.01 \, \text{g/mol} \)[/tex]
- Oxygen (O): [tex]\( 16.00 \, \text{g/mol} \times 3 = 48.00 \, \text{g/mol} \)[/tex]

Therefore, the total molar mass of [tex]\(NaHCO_3\)[/tex] is:
[tex]\[ 22.99 + 1.01 + 12.01 + 48.00 = 84.01 \, \text{g/mol} \][/tex]

2. Convert the volume of the solution from milliliters to liters:
[tex]\[ \text{Volume of solution} = 250.0 \, \text{mL} = 250.0 \, \text{mL} \times \frac{1 \, \text{L}}{1000 \, \text{mL}} = 0.25 \, \text{L} \][/tex]

3. Calculate the number of moles of [tex]\(NaHCO_3\)[/tex] in the solution:
Using the formula:
[tex]\[ \text{Moles of } NaHCO_3 = \frac{\text{mass of } NaHCO_3}{\text{molar mass of } NaHCO_3} \][/tex]

[tex]\[ \text{Moles of } NaHCO_3 = \frac{12.0 \, \text{g}}{84.01 \, \text{g/mol}} \approx 0.14284 \, \text{moles} \][/tex]

4. Calculate the molarity of the solution:
Molarity (M) is given by the formula:
[tex]\[ \text{Molarity} = \frac{\text{moles of solute}}{\text{volume of solution in liters}} \][/tex]

[tex]\[ \text{Molarity} = \frac{0.14284 \, \text{moles}}{0.25 \, \text{L}} \approx 0.571 \, M \][/tex]

Therefore, the molarity of the solution is [tex]\(0.571 \, M\)[/tex]. The correct answer from the provided choices is:

[tex]\[ \boxed{0.571 \, M} \][/tex]