How many moles of hydrogen and oxygen are in 2 moles of water?
water: h2o
# of molecules = (6.022 x 10^23)(2)= 1.2044 x 10^23
# of hydrogen atoms = (1.2044 x 10^23)(2)= 2.4088 x 10^24
# of oxygen atoms = 1.2044 x 10^24
Did I do this correctly? What do I do about significant digits since the number 2 for 2 mol is only one significant digit?
3 answers
No, you calculated the number of atoms in the molecule. The question is for moles. There are two moles of hydrogen per mole of H2O and one mole 0f oxygen per mole of H2O. Therefore, for 2 moles of H2O, there are 4 moles of hydrogen and 2 moles of oxygen.
Thank you :)
If I would have had something like 2.4 would I round it to 2 because of significant digits?
If I would have had something like 2.4 would I round it to 2 because of significant digits?
No, if you had 2.4 moles instead of 2.0, it would then be (for H) 2 x 2.4 = 4.8. In multiplication you are allowed the number of significant figures for the least significant number used. Since 2.4 has 2 s.f. and 2 moles H2O (I assume that would mean 2.000000000), then you would be allowed 2 s.f. and 2.0 x 2.4 = 4.8 moles. (5 moles as an answer would be incorrect as would be 4.80.)
1 answer