the number of molecules in 6.843*10^-2 kg of Al(NO3)3 is:
and this is what i have done so far... 1st i converted the kg to g which is 6.843*10^-5. then i figured out the moles:6.843*10^-5/213.01 i got 3.21*10^-7. i then multiplied this number by avogadro's number(6.022*10^23) my final answer was 1.933*10^17. but it is not one of my answer choices. can anyone tell me where i went wrong? thanks.
You didn't convert kg to g properly. The conversion factor is 1000 g = 1 kg. Apparently you 1 g = 1000 kg.
I didn't type all my answer. Apparently you used 1 g = 1000 kg.
6.843 x 10^-2 x (1000 g/1 kg) = 6.843 x 10^1 = 68.43 g.
To find the number of molecules in 6.843*10^-2 kg of Al(NO3)3, you followed the correct steps up to finding the moles of the compound. However, there seems to be an error in your calculation of moles.
Let's go through the steps again:
1. Convert kg to grams: 6.843*10^-2 kg * 1000 g/kg = 6.843*10^1 g
2. Determine the molar mass of Al(NO3)3:
- Aluminum (Al) has a molar mass of 26.98 g/mol
- Nitrogen (N) has a molar mass of 14.01 g/mol
- Oxygen (O) has a molar mass of 16.00 g/mol
Al(NO3)3 has 1 aluminum atom, 3 nitrogen atoms, and 9 oxygen atoms.
Molar mass of Al(NO3)3 = (1 * 26.98) + (3 * 14.01) + (9 * 16.00) = 212.98 g/mol
3. Calculate the moles of Al(NO3)3:
moles = mass / molar mass = 6.843*10^1 g / 212.98 g/mol
Now, when we plug in the values, we get:
moles = 6.843*10^1 g / 212.98 g/mol = 3.211*10^-1 mol
So, there was an error in your calculation of moles. The correct value is 3.211*10^-1 mol.
4. Finally, to find the number of molecules, multiply the moles by Avogadro's number (6.022*10^23 molecules/mol):
number of molecules = moles * Avogadro's number
number of molecules = 3.211*10^-1 mol * 6.022*10^23 molecules/mol
When you calculate this, you should get the correct answer for the number of molecules in Al(NO3)3.