问题
填空题
标出下列化合物中加点元素的化合价．
| +1 |
| H |
| P |
| ． |
| -2 |
| O |
| +1 |
| K |
| Mn |
| ． |
| -2 |
| O |
| +1 |
| H |
| S |
| ． |
| +2 |
| Ca |
| C |
| ． |
| -2 |
| O |
| Al |
| ． |
| -1 |
| (OH) |
答案
设磷酸中磷的化合价为x．
（+1）×3+x+（-2）×4=0
解得x=+5
设高锰酸钾中锰的化合价为y．
（+1）+y+（-2）×4=0
解得y=+7
设硫化氢中硫的化合价为z．
（+1）×2+z=0
解得z=-2
设碳酸钙中钙的化合价为w．
（+2）+w+（-2）×3=0
解得w=+4
设氢氧化铝中铝的化合价为m．
m+（-1）×3=0
解得m=+3
故答案为：
| +1 |
| H |
| +5 | ||
|
| -2 |
| O |
| +1 |
| K |
| +7 | ||
|
| -2 |
| O |
| +1 |
| H |
| -2 | ||
|
| +2 |
| Ca |
| +4 | ||
|
| -2 |
| O |
| +3 | ||
|
| -1 |
| (OH) |
