Please help me with chem!!!!?

Question

Ok, so I have to come up with a procedure for a lab that i have to do tomorrow. in this lab, i have to find the following: (for 10ml. of water)
1. Mass
2. How many moles
3. The number of molecules.

So, I think i have part 1. to find the mass which would be: to measure an empty graduated cylinder, fill it with 10 ml. of water, and measure it then, then subtract to find mass.

But, after that I comprehend very little on what to do with the rest.
Part 2, i thought I was told i would have to use the mass, but, i have no idea how to do it, and also how to find out how many moles.
and part three, I have no idea
So, my question would be, can you verify that Part one is the correct way to do it, and please help me with parts two and three. thanks.

Answer 1

Yes.

The scale will give you the mass (difference of cylinder full and cylinder empty).

You will also have the density (mass/volume), which is not really needed, but good to know anyway.

Do you know the molecular weight (MW) of water?

If so, you know there are "X" grams/mole. Then if you have mass (grams), just divide mass by MW and voila...you get the number of moles.

(grams) / (grams/mole) = grams * mole / grams = moles

Then do you know Avogadro's number? If so then you know that there are "X" molecules/mole. So just take the number of moles you just calculated and multiply be Avogadro's number and voila, you get the number of molecules.

moles * (molecules / mole) = molecules

Answer 2

experiment seems dumb...... but yeah
Thats how you'd do step 1.

From there i really do'nt know. I'd do it all mathematically. That might be what the experiment is asking you to do. Just figure out a way to be able to do it mathematically.

Since temperature and pressure are probably not at STP, thats probably why you need to determine the mass rather than using the STP density. at STP .. 1 ml of water is equal to about 1 gram. So your 10 mL of water should be about 10 grams, probably a little less....depends on the accuracy of scale and what not.

Once you know the mass, you divide it by its formula weight (18 g/mol) to get the moles. Then multiply by avagadro's # to get the # of molecules

So 1...weight to determine mass. By weighing empty graduated cylinder then the cylinder with water. Find the difference.

step 2. Mass (in grams) / 18 = moles
step 3. Moles * 6.02 * 10^23 = molecules

Answer 3

1. Mass - you got this right. Weigh the empty cylinder, carefully pour in 10 mL of water and reweigh and subtract the mass of the cylinder. Note that the density of water is 1 g/cm^3 or 1 g/mL. So 10 mL of water should weight 10 g. If it doesn't, you have a problem. :-)

2. How many moles is this 10 g of water? Let's start with molecular mass. Using rounded values, oxygen has an atomic mass of 16 g/mol and hydrogen has an atomic mass of 1 g/mol. You can confirm this on any periodic table. Water has a chemical formula of H2O. So that means the atomic mass of water is 18 g/mol. You now know all you need to calculate the number of moles:

10 g of water (in your cylinder) x (mol/18 g of water) = 0.56 mol.

3. The number of molecules uses Avogadro's number which is 6.023 x 10^23 molecules/mol. This number holds true for ANY element or molecule. It's a constant. So again, you have all you need to calculate the number of molecules:

0.56 mol of water x (6.023 x 10^23 molecules/mol) = 3.37 x 10^23 molecules

In essence, you have approximately half a mole of water, so your number of molecules is approximately half of Avogadro's number.

Make sense? Hope this helps!

Answer 4

a million.0 Potassium is very electropositive ingredient with low ionization potential. This factors makes the outer valance electrons ejection particularly undemanding with electric powered voltage. As you be attentive to electric powered impulses are with the aid of pass of electrons 2.0 4 moles of Al reacts with 3 moles O2 giving Aluminum oxide. this suggests that 8 moles of Al desire six moles of O2 3.0 team III era iv, probable the ingredient is Ga and the Oxide is Ga2O3 4.0 1s2 2s2 2p6 3s13Px1

Answer 5

jimvalentinojr's answer is correct - one other piece of information that may help is that water has a specific gravity of 1.00, therefore 1ml of water weighs 1g; 10ml = 10g