How to Calculate the Number of Molecules in a Given Amount of Substance
What is the formula to calculate the number of molecules in a given amount of substance?
How do you determine the number of molecules in a specific mass of a compound like in the example of 322 grams of Cu(NO3)2?
Formula for Calculating Number of Molecules
To calculate the number of molecules in a given amount of substance, you can use the formula:
N = (m / M) x NA
Where:
N = Number of molecules
m = Mass of the substance in grams
M = Molar mass of the substance in grams per mole
NA = Avogadro's number (6.02 x 10^23)
Calculating the Number of Molecules in 322 grams of Cu(NO3)2
In the given example of 322 grams of Cu(NO3)2:
The molar mass of Cu(NO3)2 is calculated as follows:
Cu = 1*63g = 63g
N = 2*14g = 28g
O = 6*16g = 96g
Total molar mass = 187g/mol
Using the formula N = (m / M) x NA:
N = (322g / 187g/mol) x 6.02 x 10^23
N = 3.92 x 10^23 molecules
Therefore, there are approximately 3.92 x 10^23 molecules in 322 grams of Cu(NO3)2.