How many moles of ca(oh)2 is 19.71 grams?
Answers
Answer:
2.66×10^-1 mol
So the formula is ca(oh)2, the number 2 which is outside the bracket applies to the elements inside the bracket only. So Ca which is calcium, Ca=40.08, O is the oxygen so it's O= 16.00×2=32 because the number 2 only applies to the elements that are inside the bracket. Now it's h turn. h is hydrogen so it's 1.01×2 = 2.02. Now you all of them together. So M which is molar mass equals 74.1g/mol. Now you use the formula to solve for the number of moles. Which is n=m/M. The question has already given the mass which is 19.71g. Now you put the variable in. So n=m/M, n=19.71 g / 74.1 g/mol. The grams unit cancel off and your left with mol. When you divide, the answer will be n=0.2659919028 mol. So the final answer has to be in 3 significant digits which is n=2.66×10^-1 mol
Hope this helps. And if you get it wrong then I'm sorry