Question

Can someone explain why these answers are correct please?
1. What is the volume of one mole of a diatomic gas at STP? - 22.4 L
2. Which of the following substances has a molar mass of 142 g? - P2O5
3. Which of the following is equal to the number of particles in 24 grams of carbon-12?- 2 moles
4. Which of the following is not a measure of the amount of matter? - STP
5. At STP, how many molecules of nitrogen gas are in 2.24 L? - 6.022 x 10^24
6. What mass will 33.6 L of nitrogen gas (N3) have at STP? - 42g
7. You do an experiment in which you need 0.25 moles of tyrosine (C9H11NO3). How many grams must you weigh out? - 45.3 g

Answer 1

@Cuanchi

Answer 2

@aaronq

Answer 3

1. What is the volume of one mole of a diatomic gas at STP? - 22.4 L

Use the ideal gas law using standard temperature and pressure and you will get the volume to equal that number.

2. Use the molar masses of the elements of the compound (found on the periodic table) and add them up.

Answer 4

for 3. and 7.

\(\sf moles=\dfrac{mass}{Molar~mass}\)

Answer 5

Thank you so much!

Answer 6

5. At STP, how many molecules of nitrogen gas are in 2.24 L? - 6.022 x 10^24

use the ideal gas law and solve for n, moles. then use:

\(\sf moles=\dfrac{particles}{avogadro's~number}\)

solve for particles (which are molecules of \(N_2\) in this case).


6. What mass will 33.6 L of nitrogen gas (N3) have at STP? - 42g

Use the ideal gas law solve for n (moles) and then use the equation from 3.

Answer 7

no problem!