Ashley Vanderpol

Hi guys,

I'm just going to go straight into it and give you some detail, I would appreciate your help and it's a little long.

We began by placing 100mL of HCl in a calorimeter (which has been calibrated), recording it's temperature and placing some magnesium powder into it, every 30 seconds we recorded the temperature until it had become constant.

RESULTS

Hydrochloric acid and magnesium powder

Before experiment: HCl by itself: 18.5 degrees

before experiment: Magnesium powder: 0.217 grams

after reaction occurred: HCl with magnesium powder: 23.5 degrees

Temperature change = 5 degrees Celsius

The calibration factor is 450J°C-1

THE REACTION

2HCl (aq) + Mg (s)  MgCO2 (aq) + H2 (g)

MY WORKING

- Case 1, (HCl + magnesium powder) we know that 100mL of HCl caused that reaction, so find the amount of Mole.

n = 0.1 / 36.46 x 2 = 0.0055 mole of HCl this means, 2250J of energy was given off by this amount of Mol of HCl

ΔH = 2250 / 0.0055 = 409kJ was released.

Therefore the enthalpy change is 409kJ

Is this right? Thanks guys :D

I have two functions within the domain [-2,2]

18+x-x^4

(x+2)(x-1)^3

Kind regards

Say for example I have a function: f(x) = x^2 + 2x. With the domain [0,3]

After deriving the function so it's f'(x) = 2x + 2. What would the domain be? Still [0,3]?

Thanks

Which of the following equations best represents a redox equation?

A) H2S(g) + 2OH-(aq) --> S(2-)(aq) + 2H2O(l)

B) SO4(2-)(aq) + H3O(+)(aq) --> HSO4(-)(aq)+H2O(l)

C) NH4(aq) + CO3(2-)(aq) --> NH3(g) + HCO3(-)(aq)

D) I2(aq) + 2OH(-) --> I-(aq) + IO(-)(aq) + H2O(l)

Any help would be gratefully appreciated

Regards, Ashley

Citric acid C6H8O7, is an acid found in the juice of many fruit. The following analysis was carried out to determine the concentration of citric acid in a sample of lemon juice.

A 25.00mL sample of the lemon juice was diluted to 100.00mL in a volumetric flask. A 20.00mL aliquot of this diluted solution was added to a 100.00mL conical flask with two drops of indicator. A burette was filled with a solution of 0.142M sodium hydroxide, NaOH and the titration produced an average titre of 11.88mL. The equation for this reaction is

C6H8O7(aq) + 3NaOH(aq) --> Na3C6H5O7(aq) + 3H2O(l)

a) Calculate the concentration, in mol L^-1, of C6H8O7 in the undiluted lemon juice.

any help is appreciated!

Kind regards, Ashley

Basically title says it all, any help is appreciated.

regards, Ashley

What volume of 0.1 M sulfuric acid would be required to neutralize a solution containing 0.5g of sodium hydroxide and 0.8g of potassium hydroxide?

Regards, Ashley

I have this question that I can't seem to figure out.

When 0.100g of white phosphorus is burned in oxygen, 0.228g of an oxide of phosphorus is produced. The molar mass of this oxide is 284.

a) What is the empirical formula of the phosphorus oxide

b) What is the molecular formula of the phosphorus oxide

Thanks for the help!

I haven't been feeling well lately, not wanting to eat, absolutely no energy (which is strange as I'm a long distance runner), lot's of dizzy spells, heaps of cramps, mainly in the legs and just general sickness in my stomach.

I have no idea what it is, and I have never felt like this before, although it's probably nothing.

Please help me clarify?

Just a quick question, I have successfully completed year 11 chemistry, I'm just wanting to know what you guys would recommend for me to get ready and prepare for year 12 chemistry.

I am currently in the process of getting some print outs for helpful tables and meanings so I can put them in my folder.

I currently have a periodic table, valency table and a oxidation-Reduction table.

What else would you guys recommend?

regards

help me transform this please

4e^x+9e^(-x)=12

regards

Can you please help me with the steps to solve this as a quadratic, I got the answer 27 or 3 although the correct answer is 1 or 3, please help me see this.

3^(2x) - 30*3^x + 81 = 0

thanks for any help given

Can you help me with this

((10a^2b^-3)^-2)/(5ab^3*(2a^2b)^-3)

or here is a picture to make it a bit easier

http://i39.tinypic.com/2dvoc41.jpg

thanks!

Can you help me with this

((10a^2b^-3)^-2)/(5ab^3*(2a^2b)^-3)

or here is a picture to make it a bit easier

http://i39.tinypic.com/2dvoc41.jpg

thanks!

thanks guys, I'm never popular and I have had a 'bad run' with females.

Though truthfully answer something for me, am I really that ugly?

http://imageshack.us/photo/my-images/593/307688232...

I have this paragraph and I would like somebody to give me some constructive criticism.

Thanks

" We near our location, our torches ready, our rope rolled and our flints packed; we began. The journey was a decent 140km from our starting location, also known as our homes, warm and comfortable waiting for us upon return. What I remember most is the roaring fire, my bed and me being devoured in a good book. "

I'm trying to improve my English skills for year 12 as it has always been my worst subject.

I wrote this sentence and I have no idea if there are ways to improve it? any help will be appreciated, thanks.

'The last encounter which took place made me feel repugnance towards the mysterious creature, undetermined on why I feel this way I continue to have persistence. I will succeed.'

Hey guys, if possible can I please have some help with this question

Find the sum of the first 7 terms of the sequence 7,12,17,22,...

any working out will also be greatly appreciated, thanks

help please?

please help!

~Regards