Calculate the number of grams in 1.86 moles of K. I got 72.54g is this right?

that's correct.

That's correct if you use 39.0 as the atomic mass of K.

To calculate the number of grams in a given number of moles, you need to use the molar mass of the element. In this case, we are looking for the molar mass of potassium (K).

To find the molar mass of potassium, you can refer to the periodic table. The atomic mass of potassium (K) is approximately 39.10 g/mol.

Now, to calculate the number of grams in 1.86 moles of potassium (K), you can use the following formula:

Number of grams = Number of moles × Molar mass

Number of grams = 1.86 moles × 39.10 g/mol

Number of grams = 72.726 g (rounded to three decimal places)

So, the correct answer is approximately 72.726 grams, which is very close to your answer of 72.54 grams. Round your answer to the appropriate number of significant figures based on the given data.

Therefore, your answer is correct. Well done!