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Just took a chemistry test, had a few I wasn't sure of:

When hydrogen and oxygen gas combine to form water vapor, what mass of water forms if 10grams of oxygen reacts completely?

[tex] 2H_2 + O_2 \rightarrow 2H_2O [/tex]

10 grams of oxygen is .625 moles, and the stoichiometric ratio is 1:2, so 1.25 moles of water form. 1.25 moles of water has mass 22.5g, but that wasn't one of the options.

If one mole of Cl2, SO3, H2, and Br2 are placed in the same container, what is NOT the same for each?

a) Average KE

b) Average velocity

c) Gas molecules

d) Vapor (or partial) pressures

I put D, because a & b are analogous to each other, and rely on temperature. I almost put c, I caught myself by remembering that a mole of a substance has the same number of gas molecules, but my thinking was for example SO3 has twice as many atoms as the others.

A face centered cubic holds how many atoms in a unit cell?

One from the corners and the 6 halves on the sides makes 4, right?

Which of the following has the lowest freezing point?

1 m (molality) AlCl3

1 m NaCl

1 m NaPO4

couple others

I know that a solution's FP and BP change when dissolved, so I figured the one with the most dissolved molecules would have the lowest freezing point. I think I put AgCl3.

Given the graph of four solutions (Vapor pressure vs temperature), which has the weakest intermolecular forces?

Solution A had a pretty steep exponential slope, solutions B & C were inbetween, and solution D had a very very shallow exponential slope. I said A, because strong intermolecular forces means its hard to break the bonds in the liquid to form vapor, so the inverse is true also.

Thanks.

When hydrogen and oxygen gas combine to form water vapor, what mass of water forms if 10grams of oxygen reacts completely?

[tex] 2H_2 + O_2 \rightarrow 2H_2O [/tex]

10 grams of oxygen is .625 moles, and the stoichiometric ratio is 1:2, so 1.25 moles of water form. 1.25 moles of water has mass 22.5g, but that wasn't one of the options.

If one mole of Cl2, SO3, H2, and Br2 are placed in the same container, what is NOT the same for each?

a) Average KE

b) Average velocity

c) Gas molecules

d) Vapor (or partial) pressures

I put D, because a & b are analogous to each other, and rely on temperature. I almost put c, I caught myself by remembering that a mole of a substance has the same number of gas molecules, but my thinking was for example SO3 has twice as many atoms as the others.

A face centered cubic holds how many atoms in a unit cell?

One from the corners and the 6 halves on the sides makes 4, right?

Which of the following has the lowest freezing point?

1 m (molality) AlCl3

1 m NaCl

1 m NaPO4

couple others

I know that a solution's FP and BP change when dissolved, so I figured the one with the most dissolved molecules would have the lowest freezing point. I think I put AgCl3.

Given the graph of four solutions (Vapor pressure vs temperature), which has the weakest intermolecular forces?

Solution A had a pretty steep exponential slope, solutions B & C were inbetween, and solution D had a very very shallow exponential slope. I said A, because strong intermolecular forces means its hard to break the bonds in the liquid to form vapor, so the inverse is true also.

Thanks.

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