3)-4
1)- 3
2)-1............................................
2. Серебряная монета
5. Медная проволока
<span>Дано:</span>
w(Cr) = 35,37\%
w(P) = 21,1\%
O
<span>Найти: CrxPyOz</span>
Решение:
<span>w(O) = 100\% - (w(P) + w(Cr)) = 100\% - (35,37\%
+ 21,1\%) = 43,53\%</span><span>
</span><span>n(Cr) = 35,37\%\52
= 0,68</span>
<span>n(P) = 21,1\%\31 =
0,68</span>
<span>n(O) = 43,53\16 = 2,72</span>
<span><span>CxHy = n(Cr) : n(P) : n(O) = 0,68 : 0,68 : 2,72 = 1: 1: 4 = </span>→ Cr1P1O4</span>
<span>Ответ: CrPO4 - ортофосфат хрома (III)</span>
1) 5KI + 3H2SO4 + KIO3 = 3K2SO4 + 3I2 + 3H2O, баланс:
I- -e- = I | 1 | 5 | 5 |
I+5 +5e- = I | 5 | | 1 |;
2) FeS2 + 8HNO3 = Fe(NO3)3 + 5NO + 2H2SO4 + 2H2O, баланс:
Fe+2 -e- = Fe+3
2(S)-1 -14e- = 2S+6 | 15 | 15 | 1 |
N+5 +3e- = N+2 | 3 | | 5 |.