Mr Beaumont booklet on moles

Task 1.2c (second sheet)
Question 3
What mass of glucose can be fermented to give 5.00g of ethanol?
C6H12O6 (aq) ---> 2C2H5OH (aq) + 2CO2 (g)

I thought I knew how to do this sort of question, but I got a different answer from the one on the sheet, and can't work out where I went wrong.
This is what I did:
Relative molecular mass of ethanol = 24 + 5 + 16 + 1 = 46
Moles of ethanol = mass/relative molecular mass = 5/46 = 0.109 mol
Moles of glucose = 1/2 * moles of ethanol = 1/2 * 0.109 = 0.0543 mol
Relative molecular mass of glucose = (6 * 12) + 12 + (6 *16) = 180
Mass of glucose = moles * relative formula mass = 180 * 0.0543 = 9.78g

The final answer on the sheet is 8.91g.
Thanks.

Titrations Green Question Paper

Question 5
On the answers it says you multiply the moles of IO3(-), which is 2.3 x 10^-3, by the molar mass of iodine. Isn't it I2, and so you would multiply by not 127, but 127 x 2?
Is it because the iodine is involved in a compound and so we use simply the molar mass of I, not I2??

Simple Molecular Structures Solubility

They are soluble in non-polar solvents because van der waal's forces form between the simple structure & the solvent, which allows a solution to form.
But are they soluble in polar solvents?
If not, why not, if yes, why?
cheers

Ionic Equation?

What is an ionic equation?
(Practice Exam Q's on titrations, Question 4)
It says 'sodium thiosulphate' but there's no 'Na' in the equation!!

Monday 13th

Is mrs Sudbery going to be in on monday, for some reason i didnt think she was.
But anywho, if she isnt in then are we still going to be doin the presentations, whos doing it, and what is it about ? just so i can get some backgroung knowlage.

thanks evreyone.
mikey

p.s did anyone else actually do the green sheets in the time limit (1point=1min), on every one i was out by about 5 mins. is that the actual amout of time we get in the exam, because if so, them methinks i need more practice.

RSC Online Chemistry 'Check-up'

Just a reminder that there's just one week left for you to take the Royal Society of Chemistry's online Chemistry 'check-up'. It's aimed at students like you, who have just started doing AS Chemistry and the deadline is 19th October.

The website link is: http://www.rsc.org/education/teachers/learnnet/olympiad_l6checkup.htm

It consists of 40 multiple choice questions of varying difficulty which test knowledge and understanding of some of the important fundamental topics in chemistry. The test can be taken several times by the same student and there is no time limit for each attempt. At the end of the test, students receive individual feedback (by email) on their performance - broken down into the main areas of chemistry. This is intended to help improve understanding and learning. Teachers will receive this feedback directly if their email address is entered when prompted.

Orbitals

In Mr Beaumont's lesson we were doing orbitals. He showed us how P orbitals and how they go in X, Y and Z directions, but how do the electrons actually go around in them because they cannot go to the origin like the diagram showed because isn't that where the nucleus is? I am confused about it.

electron pairs

i was trying to think of why there are electron pairs.
is the reason: that sub shells have electrons in pairs, and so this is why the electrons are in pairs.
what happens if there are 3 electrons in the outer shell spare? there will be one pair and then one lone electron? what happens with the repulsion there?
and then there area bonded electron and a lone electron pair, how does that happen?

Shapes of Molecules

in my notes it says that we count the number of electron pairs to see what the shape of molecule is classed as.
e.g. H2O would actually be classed as tetrahedral, as it has two lone pairs and two bonded pairs.
In the book it says that H2O is actually classed as non-linear.
I have guessed that the shape of molecule is possibly classed by the amount of bonded pairs? not the amount of pairs overall?

also i have presumed that if it has four bonded pairs, the angle will be 109.5
But then if it has three bonded pairs, and then one lone pair, the new angle would then become 107.5 . . . . .

Pink support sheets

On the last page of the pink booklet (mole calculations)
Question 3a is How many moles of hydrogen in every mole of HCl?
What does this mean? Because surely it's a compound so to work out moles of hyrdogen is meaningless. Am I missing something here?
Thanks.

Intermolecular forces presentation

Hi
We're working on our intermolecular forces presentation but have some questions as follows:
Why does boiling point decrease going down Group 0?
When talking about dipoles, do we have to explain why they exist with reference to core charge?
Do we have to cover hydrogen bonding or the covalent character of ionic bond?
How do you pronounce van der waals and delta.
Apart from that, we're fine!
See you on Monday.
jo
x

Catching up...

Just to check, what should I know, so that if I have forgotten to do anything i still have this weekend to do it?

Bita moles

In beaumonts lesson we did the find the relative atomic mass of an unkown metal by gas collection.
x (unkown metal) = 0.20 g
1MHCL we used 25cm3
Volume of hydrogen gas we found out was 192 cm3 (in my experiment).
Equation was : x + 2HCl = xCl2 + H2
We were told to find the relative atomic mass of x, which I found was 25 (in my experiment)

On the sheet for the experiment that we were given, one question is "Calculate amounts in moles (using your value Ar for x) to show that the acid was in excess".
any ideas on this one? when i converted moles of HCl (which i found by multiplying moles of x by two) to volume (v=24000n) i found it was way greater than the 25cm3 we used. how do i do it:S?