can any of you older guys help me with this chemistry?!?!

[thefifthfreedom]

ive got 4 problems that i cant solve maybe you guys know how to do them...

1. THe compound calcium cyanamide (CaNCN) can be used as a fertilizer. To obtain this compound, calcium carbide is reacted with nitrogen at high temperatures.

CaC2 + N2 ---> CaNCN + C

What mass of CaNCN can be produced if 7.50 mol CaC2 reacts with 5.00 mol N2?

2. When copper(II) oxide is heated in the presence of hydrogen gas, elemental copper and water are produced. What mass of copper can be obtained if 32.0 g copper (II) oxide is used?

3. Determine the theoretical and percent yield of hydrogen gas if 36.0 g water undergoes electrolysis to produce hydrogen and oxygen and 3.80 g hydrogen is collected.

4. The Swedish chemis Karl Wilhellm was first to produce chlorine in the laboratory.

2NaCl (s) + 2 H2SO4 (aq) + MnO2 (aq) ---> Na2SO4 (aq) + MnSO4 (aq) + 2 H2O (l) + Cl2 (g)

What mole ratio could be used to find the moles of chlorine produced from 4.85 moles of sodium chloride? Determine the moles of chlorine produced. Determine the mass of chlorine produced.

i dont know how to do these but id appreciate it if you guys could help

[LadyStarlight]

These are basic......

1) figure out the limiting reagant (in second question, figure out moles that the 32 g is equal.....etc...)
2) figure out the moles yielded based on the amount of the limiting reagant
3) convert the moles to mass

They are all similar, jsut some such variations.......read the text and you'll be able to do it.

[1stindoor]

These are basic......

A hot body and a smoking brain...you're like the total package.

[GameDayDog]

A hot body and a smoking brain...you're like the total package.

Hahaha.. bump that... I thought this thread was gonna be about counting protein or sumphin'... She said - These are basic!!!! hahaha... I haven't seen a periodic table since the last tyme I was in the furniture store...

Way 2 Go LadyStarlight...

Peace..
~G

[chizzled1419]

These are basic......

1) figure out the limiting reagant (in second question, figure out moles that the 32 g is equal.....etc...)
2) figure out the moles yielded based on the amount of the limiting reagant
3) convert the moles to mass

They are all similar, jsut some such variations.......read the text and you'll be able to do it.

Showoff

[josh jr]

I had a couple of moles in my front yard last year..I converted them to dead.

[r8rrob]

These are basic......

1) figure out the limiting reagant (in second question, figure out moles that the 32 g is equal.....etc...)
2) figure out the moles yielded based on the amount of the limiting reagant
3) convert the moles to mass

They are all similar, jsut some such variations.......read the text and you'll be able to do it.

I was going to say the same thing!

[stahlhart]

1. THe compound calcium cyanamide (CaNCN) can be used as a fertilizer. To obtain this compound,
calcium carbide is reacted with nitrogen at high temperatures.

CaC2 + N2 ---> CaNCN + C

What mass of CaNCN can be produced if 7.50 mol CaC2 reacts with 5.00 mol N2?

Approximate atomic weights in question:

Carbon (C) = 12
Nitrogen (N) = 14
Calcium (Ca) = 40

One mole (Avogadro's Constant, or 6.022 x 10**23) of an element will weigh what its atomic weight is in grams; in other words, 1 mol of carbon will weigh 12g. Since nitrogen molecules are stable as pairs of individual nitrogen atoms, 1 mol of nitrogen here will be equal to 2 x 14 = 28 grams, so 5.00 mol of N2 will weigh 140 grams. Similarly, 1 mol of calcium carbide will weight (1 x 40) + (2 x 12) = 64 grams, and 7.50 mol will weigh 480 grams.

Since the equation for the reaction is balanced, the amounts of the individual atoms and molecules on both sides of the "-->" equal one another. So it's just a matter of determining which of the two you run out of first on the left side, because once you run out of calcium carbide or nitrogen, no further reaction will take place (this must be the limiting reagent that LadyStarlight is referring to). Here, I would guess that the nitrogen is going to limit the reaction, because there are fewer molecules of it than there are of the calcium carbide. So if all 5.00 mol of the nitrogen is used up here, then there are 5.00 mol of calcium cyanamide, or 5 x ((1 x 40) + (2 x 14) + (1 x 12)) = 400 grams produced.

This seems to work out, because if the 5.00 mol of N2 were completely consumed, then 5.00 mol of CaC2 would also be consumed, and 5.00 mol of CaC2 weighs 320 grams. So you have

320g CaC2 + 140g N2 --> 400g CaNCN + 60g C (460g total on both sides)

...and there would be 5.00 mol of carbon left over, and 5.00 x 12 = 60g.

You should be able to figure out the rest of them much the same way.

C.K.

[GREENFEATHER]

I had a couple of moles in my front yard last year..I converted them to dead.

I had one in the sink that I converted to dead with the toilet plnger handle!

[Hibiscus09]

We used to take the glass stirring stick things and melt them over the bunsen burner trying to make shapes out of them. We also put grooves in the sides of hot fire balls (back when they didn't do knife searches -- LOL) and then shoot them up to the blackboard with a rubber band. It made a really loud noise! That scared the crap out of Mr. Nance. I don't think I actually ever did chemistry in chemistry class.

[~*IronBelle*~]

I never did chemistry class. LOL!

[Capt. America]

And they say weightlifters are stupid!