Tuesday
December 10, 2013

# Posts by Gemma

Total # Posts: 59

chemistry
Molarity = moles/volume (dm3) so you need to convert your volume into dm3. 1dm3 = 1000ml so your equation should be; molarity = 0.56/0.100 = 5.6moldm-3

chem
Not sure about the KBr and the sand but iron is magnetic so that can be removed with a magnet. Sorry I cannot answer fully.

chemistry
standard enthalpies of formation H20(l) = -286 LiOH(s) = -487 standard enthalpies of solution for LiOH(s) to split into it's ions is 21 all values are in KJmol-1 Use the data given to calculate a value for the enthalpy change for the reaction of lithium with water. I get h...

Chemistry
The first step would be to calculate the MR's of each substance so you could get the reacting masses so: 3H2 = (3 x 2 x 1) = 6 N2 = 14 x 2 = 28 2NH3 = (2 x 14) + (2 x 3 x 1) = 34 so in theory you need 6litres of H2 and 28litres of N2 to produce 34litres of NH3. Is the ques...

Chemistry
first of all you would need to find out the number of moles in solution using moles = mass/Mr Mr of AgNO3 = 108+14+(16x3) = 170 moles = 1.70g/170 = 0.01 Then you can use the formula: concentration = moles/volume(dm3) = 0.01/0.250 = 0.04moldm-3 hope this helps

chemistry
You need to know the formula for silver nitrate which is AgNO3 Then you work out the MR of silver nitrate = 108+14+(16x3) = 170 Then you work out the MR of the nitrogen contained in silver nitrate. There is just one nitrogen atom so it would be 14. Then you need to work out th...

chemistry
Use the formula moles = mass/Mr Mr of sodium = 23 Rearrange the equation to make mass the subject. mass = moles x Mr and put in the numbers... mass = 2 x 23 = 46g Hope this helps

Chemistry
Electrostatic bonding forces relates to covalent compounds and the shared pair of electrons, it is when the nucleus of one atom attracts the electron of another atom and the electrons become shared between the two atoms. All you need to do now is pick out the covalent compound...

Chemistry
A biomass power station burns forestry residue which has 2000 ppm potassium in it and produces 2% ash by weight (think Ive worded that right). I need to find the fraction of K2O in the ash, but only the fraction of K in the fuel as a whole is given.

Art
I need to know about the symbolism in Olympia, can you explain what this means please.

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