Mass-mass+and+Mass-volume+relationships

To convert between mass and moles of a substance use the equation: n=m/M. The n means the number of moles of the substance. m is the mass of the substance you want to weigh. M is the mass of the substance’s original molar mass

To convert between mass and moles of a substance use the equation: n=m/M. The n means the number of moles of the substance. m is the mass of the substance you want to weigh. M is the mass of the substance’s original molar mass Sample problem: How many moles are there in 7.45x10e24 molecules of NO2 Solution: You must use the number 7.45x10e24 molecules/6.02x10e23, the answer should be 12.4 moles. For more sample problems look at 7.1 in the Chemistry Book

2. Use the mole to convert among measurements of mass, volume, and number of particles.

- mass = gam/gfm/gmm - volume = mole x 22.4 - number of particles = NA =n*6.02x10e23

Sample Problems:

Determine the volume of 2 moles of Nitrogen gas at STP

Formula : number of moles x 22.4

2 x 22.4 = 44.8 g/mol

Determine the number of nitrogen molecules in 423g of nitrogen gas.(N2)

Formula : 423g / the mass of N2 (28.02g) = about 15.10 mol N2

3) Mass molar: is the mass of one mole of the substance. Volume: it's a gas and measured in STP. STP: Stands for standard temperature and pressure. The volume of a gas varies with a change in temperature or a change in pressure. Because of this variation, the volume of a gas is usually measured in STP.