Suppose you have two samples that are equal in weight, 21.3 g Ti and 21.3 g Cr2O3 .
Calculate the number of moles of each substance.
For Ti I got .444 and for Cr2O3 I can't get the answer for some reason.
I did 151.989/21.3 and got 7.13 but it shows up as incorrect, but I did the same steps as I solved for Ti. Could someone help where I went wrong?
For Ti I did 21.3/47.9 and got .444
Nevermind I realize where I went wrong ): Careless mistake haha
No, you didn't do the same step.
mols = grams/molar mass
To calculate the number of moles for a substance, you need to use the molar mass of that substance. The molar mass is defined as the mass of one mole of a substance and is usually given in grams per mole (g/mol).
For titanium (Ti), the molar mass is approximately 47.9 g/mol. To calculate the number of moles of Ti, you correctly divided the mass (21.3 g) by the molar mass (47.9 g/mol), resulting in approximately 0.444 moles.
Now, let's calculate the number of moles for chromium(III) oxide (Cr2O3). The molar mass of Cr2O3 can be calculated as follows:
Molar mass of Cr: 52.0 g/mol
Molar mass of O: 16.0 g/mol (x3 since there are three oxygen atoms in Cr2O3)
Molar mass of Cr2O3 = (2 x 52.0 g/mol) + (3 x 16.0 g/mol) = 152.0 g/mol
Now that we have determined the molar mass of Cr2O3, we can calculate the number of moles. Dividing the mass (21.3 g) by the molar mass (152.0 g/mol) should give you the correct answer.
21.3 g / 152.0 g/mol ≈ 0.140 moles
It seems you made an error in your calculation for Cr2O3. Make sure to double-check your work, including the molar mass calculation, and perform the calculation again.