Mass and Composition of Compounds

The video tutorial explains how to calculate the mass of a specific element in a compound using two methods: percent composition and stoichiometry. It demonstrates these methods with examples, including calculating the mass of carbon in C2H4 and nitrogen in NH3. The tutorial emphasizes understanding molar mass and converting between grams and moles to find the desired element's mass.

What is the first step in finding the mass of a specific element in a compound?

• Find the density of the compound

• Calculate the molar mass of the compound

• Measure the temperature of the compound

• Determine the volume of the compound

How do you calculate the percent composition of carbon in C2H4?

• Divide the mass of carbon by the total mass of C2H4

• Multiply the mass of carbon by the total mass of C2H4

• Subtract the mass of hydrogen from the total mass of C2H4

• Add the mass of carbon and hydrogen in C2H4

What is the molar mass of C2H4?

• 24 grams

• 32 grams

• 28 grams

• 30 grams

In the picket fence method, what is the first conversion step?

• Convert moles of the compound to liters

• Convert moles of the compound to grams

• Convert grams of the compound to liters

• Convert grams of the compound to moles

What is the molar mass of ammonia (NH3)?

• 16 grams

• 17 grams

• 14 grams

• 18 grams

How do you find the percent of nitrogen in NH3 using percent composition?

• Subtract the mass of hydrogen from the total mass of NH3

• Add the mass of nitrogen and hydrogen in NH3

• Multiply the mass of nitrogen by the total mass of NH3

• Divide the mass of nitrogen by the total mass of NH3

What is the percent composition of nitrogen in NH3?

• 70%

• 60%

• 50%

• 80%

In the picket fence method for NH3, what is the mass of nitrogen in one mole?

• 3 grams

• 17 grams

• 28 grams

• 14 grams

What is the final mass of nitrogen obtained from 2.8 grams of NH3 using the picket fence method?

• 2.0 grams

• 2.31 grams

• 2.5 grams

• 3.0 grams

Which method can be used to find the mass of an element in a compound?

• Only percent composition method

• Both percent composition and picket fence methods

• Only picket fence method

• Neither method