How many sig figs is 820 g of carbon (which has molar mass 12.01) supposed to have when converted to moles?

I would use two sig figures. 820 is two sig figures.

So do I write 68.2764363 as 68?

To determine the number of significant figures in the conversion from grams to moles, you need to consider the given value and the molar mass of carbon.

First, let's calculate the number of moles using the given information:

Molar mass of carbon (C) = 12.01 g/mol

Number of moles (n) = Given mass / Molar mass

n = 820 g / 12.01 g/mol = 68.2764354704 mol

When converting from grams to moles, the number of significant figures is determined by the given value. In this case, "820 g" has three significant figures.

Therefore, the number of significant figures in the conversion to moles is also three. The answer is 68.3 mol, considering three significant figures.