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    I would be really grateful if anyone can help me answer any of the following questions :hmmmm:

    - Can you explain why the mass of aluminium in aluminium hydride is a lot greater than the mass of hydrogen, even though there are three hydrogen atoms to every one aluminium atom in the compound?

    - How much uranium would you get from 1000g of uranium oxide?

    - How many moles of ions are there in 117g of sodium chloride?

    - How many moles of electrons are there in 24 125 coulombs?

    - If 25g of calcium carbonate is heated, calculate the mass of calcium oxide produced and the volume of CO2 produced (measured at room temp and pressure).

    - What mass of sulphur dioxide will be produced when 4g of sulphur is burnt in oxygen. What will be the volume of this gas at room temp and pressure?

    - What volume of H2S will react with 20dm3 of SO2 at room temp and pressure and what mass of sulphur with be formed?

    Thanks in advance
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    1st one is because aluminium atoms are heavier (more neutrons etc.)
    The others, you need to do mole calculations, which you would have done in GCSE.
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    1) Aluminium has a Mr of 27 and Hydrogen's Mr is 1 so even with 3xH the Mr is less.

    2) 1000g of UO2

    So mass/mr gives mols of UO2 ..... 1000/270 = 3.7 Mols

    mol x Mr = mass 3.7 x 238 = 880.6g of Uranium.

    3) Na+ and Cl- are both ions, so mass/mr = mols 117/58.5 = 2 Mols

    4) not a clue sorry.....

    5) balanced equation = CaCO3 = CaO + CO2

    Ratio of 1mol : 1mol

    25/100 = .25

    therefore .25 x 56 = 14g

    CBA to do anymore but hope the ones ive done help, sorry if there are mistakes im doing it from memory and havent done any of these calculations in a while
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    - How many moles of electrons are there in 24 125 coulombs?

    You need the Faraday constant to solve this; it is the magnitude of electric charge per mole of electrons and equals (approximately) 96,485 C per mol.

    Charge of 1 mole of electrons = 96485 C
    So if you have 24125 C then you have 24125/96485 = 0.250 moles
 
 
 
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