If 0.25 grams of sodium borohydride are used for this reaction, how many moles of sodium borohydride were added?
The correct answer and explanation is:
To calculate how many moles of sodium borohydride (NaBH₄) were added, we will use the formula: Moles=MassMolar Mass\text{Moles} = \frac{\text{Mass}}{\text{Molar Mass}}
Step 1: Identify the mass of sodium borohydride
From the question, the mass of sodium borohydride is given as 0.25 grams.
Step 2: Calculate the molar mass of sodium borohydride
Sodium borohydride (NaBH₄) consists of:
- Sodium (Na) with an atomic mass of approximately 23.0 g/mol,
- Boron (B) with an atomic mass of approximately 10.8 g/mol,
- Hydrogen (H) with an atomic mass of approximately 1.008 g/mol, and
- Four hydrogen atoms from the borohydride part, each with a mass of 1.008 g/mol.
Thus, the molar mass of NaBH₄ is: Molar Mass of NaBH₄=23.0+10.8+(4×1.008)=23.0+10.8+4.032=37.832 g/mol\text{Molar Mass of NaBH₄} = 23.0 + 10.8 + (4 \times 1.008) = 23.0 + 10.8 + 4.032 = 37.832 \text{ g/mol}
Step 3: Calculate the moles of sodium borohydride
Now that we know the mass and the molar mass, we can calculate the number of moles: Moles of NaBH₄=0.25 grams37.832 g/mol≈0.00661 moles\text{Moles of NaBH₄} = \frac{0.25 \text{ grams}}{37.832 \text{ g/mol}} \approx 0.00661 \text{ moles}
Final Answer:
The number of moles of sodium borohydride added is approximately 0.00661 moles.
Explanation:
Moles are a measure of the amount of substance, and the relationship between mass and moles allows chemists to quantify how much of a substance is present. To convert mass into moles, we need to know the molar mass of the substance. By dividing the mass of sodium borohydride by its molar mass, we get the number of moles that were used in the reaction.