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Basic chemistry help!?

I'm new to chemistry and am struggling with a bit of this stuff... Any help would be very appreciated!

1. If limestone (calcium carbonate) and clay (aluminum silicate) are mixed together and heated then the result is cement. Cement is a mixture of calcium oxide, carbon dioxide, aluminum oxide, and calcium silicate.

If a factory has 100kg of clay, then how much limestone will they need to exactly react with the clay to produce cement?

2. Chromium compounds exhibit a variety of bright colors. When solid ammonium dichromate is ignited, in reaction it decomposes into nitrogen gas, water vapour and solid chromium (III) oxide. If 10kg of ammonium dichromate is used, then how many grams of nitrogen gas will be formed at standard temperature and pressure? Assume that the molar volume of the gas is 22.42L at standard temperature and pressure, what volume will the nitrogen gas formed, occupy?

These all have to be done with significant digits and units.

I meet with my tutor tomorrow,please help

1 Answer

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  • 1 decade ago
    Favorite Answer

    1. If limestone (calcium carbonate)

    if youi can give the % limestone, or the ratios on a small scale, we can scale it up to how much is needed fo 100Kg

    ==========================

    2.

    1 (NH4)2Cr207 (@ 252.07 g/mol) --> 1 N2 ( @ 28.01g/mol)

    . If 10kg of ammonium dichromate, then how many grams of nitrogen gas will be formed at standard temperature and pressure?

    10 ,000g (NH4)2Cr207 @ 28.01 g N2 / 252.07 g (NH4)2Cr207 =

    your answer: 1111 grams of N2 will be produced,

    now unless your "10Kilograms" is 10. or 10.0 or 10.00, you only have 1 sigfig in "10"

    & your answer would need to be rounded off to 1000 grams of N2

    ================================

    Assume that the molar volume of the gas is 22.42L at standard temperature and pressure, what volume will the nitrogen gas formed, occupy?

    1111 grams N2 @ 28.01 g/mol = 39.68 moles of N2

    39.68 moles @ 22.42 litres/mol =

    your answer: 889.5 litres

    again you have 4 sigfigs everywhere except in the "10KG" whic at present has only 1 sigfig.... so unless it really had more significance, you should round off to 900 litres

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