A 200g alloy is made of copper and zinc. the number of copper atoms is 3 times that of zinc,
a)calculate the number of copper and zinc atoms.
b)calculate the weight of copper and zinc in the alloy.
so for a) can i assume that the mol ratio is cu:zn = 3:1?
if so, i solved it using:
200/(65.55x3+65.42)=0.763
no. of cu atoms = 3x0.763x6.02e23
no. of zn atoms = 0.763x6.02e23
am i right?
in that case weight for both will be ~150g and 50g
looks good
To calculate the number of copper and zinc atoms in the alloy, you can assume that the mole ratio between copper (Cu) and zinc (Zn) is 3:1.
To find the weight of copper and zinc in the alloy, you can use this ratio along with the atomic masses of copper and zinc.
a) To calculate the number of copper and zinc atoms:
Let's assume the mass of the alloy is 200 grams.
First, calculate the mass of copper and zinc in the alloy using the mole ratio:
Mass of Cu = (3/4) * (200) = 150 grams (approx.)
Mass of Zn = (1/4) * (200) = 50 grams (approx.)
Next, calculate the number of moles of copper and zinc:
Number of moles of Cu = (150 grams) / (atomic mass of Cu)
Number of moles of Zn = (50 grams) / (atomic mass of Zn)
Since we don't have the specific atomic masses of copper and zinc, I will assume the values you mentioned (65.55 g/mol for Cu and 65.42 g/mol for Zn).
Number of moles of Cu = (150 grams) / (65.55 g/mol) = 2.29 moles (approx.)
Number of moles of Zn = (50 grams) / (65.42 g/mol) = 0.76 moles (approx.)
Finally, calculate the number of copper and zinc atoms using Avogadro's number (6.02 x 10^23 atoms/mol):
Number of Cu atoms = (2.29 moles) * (6.02 x 10^23 atoms/mol)
Number of Zn atoms = (0.76 moles) * (6.02 x 10^23 atoms/mol)
b) To calculate the weight of copper and zinc in the alloy:
The weights you mentioned (150g and 50g) are correct.
So, your calculated values for the number of copper and zinc atoms seem to be correct, assuming the atomic masses of copper and zinc are approximately 65.55 g/mol and 65.42 g/mol, respectively. And the weights of copper and zinc in the alloy are approximately 150 grams and 50 grams, respectively.