Final answer:
There are 0.0510 moles of potassium dichromate in 15.0 g of K₂Cr₂O₇. To make a solution with a certain number of moles, multiply the number of moles by the molar mass to find the equivalent mass in grams.
Step-by-step explanation:
To determine how many moles of potassium dichromate, K₂Cr₂O₇, are present in 15.0 g of the compound, we use the formula:
Number of moles = mass of compound (g) / molar mass of compound (g/mol)
Given that the molar mass of K₂Cr₂O₇ is 294.2 g/mol, we calculate as follows:
Number of moles = 15.0 g / 294.2 g/mol =
The correct answer is 0.0510 mol, option a).
If you need to make a solution containing 1.8 moles of potassium dichromate, simply multiply the number of moles by the molar mass to find how many grams you need to measure. This way, you can use your balance, which is calibrated in grams, to accurately measure out the amount of potassium dichromate required for your solution.