1) Высчитайте массу сульфида алюминия, который можно получить из 27г алюминия.

1)

дано

m(AL) = 27 g

----------------------

m(Al2S3)-?

2Al+3S--gt;AL2S3

M(Al) = 27 g/mol

n(AL) = m(AL) / M(Al) = 27 / 27 =1 mol

2n(Al) = n(AL2S3)

n(Al2S3) = 1 / 2 = 0.5 mol

M(Al2S3) = 150 g/mol

m(Al2S3) = n*M  =0.5 / 150 = 75 g

ответ 75 г

2)

дано

m(NaBr) = 68 g

----------------------

m(Br2) =?

2Na+Br2--gt;2NaBr

M(NaBr) = 103 g/mol

n(NaBr) = m/M = 68 / 103 = 0.66 mol

n(Br2) = 2n(NaBr)

n(Br2) = 0.66 / 2 = 0.33 mol

M(Br2) = 80*2 = 160 g/mol

m(Br) = n*M = 0.33 *160  = 52.8 g

ответ 52.8 г

3)

дано

m(Mg3P2) = 110 g/mol

------------------------------

m(Mg)-?

2P+3Mg--gt;Mg3P2

M(Mg3P2) = 134 g/mol

n(Mg3P2) = m/M = 110 / 134 = 0.82 mol

n(Mg3P2) = 3n(Mg)

n(Mg) = 3*0.82 = 2.46 mol

M(Mg) = 24 g/mol

m(Mg) = n*M = 2.46 * 24 = 59.04 g

ответ 59.04 г