1. How many moles are in 15.3 grams of Arsenic? (As: 74.922 g/mol)
2. How many grams are in 215 moles of HBr? (H: 0.998, Br: 79.904 g/mol)
3. How many grams are in 4.5 moles of KI? (K: 39.098, I: 126.9045 g/mol)
4. How many moles are in 51.37 grams of Al(OH)3 ? (Al: 26.982, H: 0.998, O: 15.998 g/mol)
The calculation of moles from grams and vice versa using the formula, mass = moles x molar mass gives us 0.204 moles of Arsenic from 15.3 g; 17425.74 g of HBr from 215 moles; 748.51025 g of KI from 4.5 moles; and 0.66 moles of Al(OH)3 from 51.37 g.
Understanding Molar Mass Calculations in Chemistry
Moles to Grams Conversion:
To convert from grams to moles or vice versa, we use the formula mass = moles x molar mass. This formula helps us determine the amount of substance present based on its mass and molar mass.
Calculating Moles from Grams:
1. For Arsenic (As) with a molar mass of 74.922 g/mol:
Given mass = 15.3 grams
Moles = Mass / Molar mass = 15.3 / 74.922 = 0.204 moles
2. For HBr with molar masses of H (0.998 g/mol) and Br (79.904 g/mol):
Given moles = 215 moles
Mass = Moles x (Molar mass of H + Molar mass of Br) = 215 x (0.998 + 79.904) = 17425.74 grams
3. For KI with molar masses of K (39.098 g/mol) and I (126.9045 g/mol):
Given moles = 4.5 moles
Mass = Moles x (Molar mass of K + Molar mass of I) = 4.5 x (39.098 + 126.9045) = 748.51025 grams
4. For Al(OH)3 with molar masses of Al (26.982 g/mol), H (0.998 g/mol), and O (15.998 g/mol):
Given mass = 51.37 grams
Molar mass of Al(OH)3 = Al + 3(H) + 3(O) = 26.982 + 3*(0.998 + 15.998) = 78.004 g/mol
Moles = Mass / Molar mass = 51.37 / 78.004 = 0.66 moles
Summary:
In conclusion, converting between moles and grams in chemistry involves using the formula mass = moles x molar mass. By understanding these calculations, you can accurately determine the amount of a substance based on its mass and molar mass.