二氧化碳是导致温室效应的主要气体，也是一种宝贵的资源。用CO2和NH3来合成尿素[CO(NH2)2]是固定和利用CO2的成功范例，其反应的化学方程式为：
CO2+2NH3=====一定条件CO(NH2)2+H2O。
请计算下列问题：
(1)若用CO2和NH3生产900 t尿素，理论上可固定CO2的质量是多少吨?
(2)2 t含尿素90%的化肥(杂质不含N)中，含氮元素的质量是多少吨(精确到0.1 t)?
解：(1)设可固定二氧化碳的质量为x。
CO2+2NH3=====一定条件CO(NH2)2+H2O
44 60
x 900 t
4460=x900 t
x=660 t
(2)2 t×90%=1.8 t
方法一：
1.8 t×Ar(N)×2Mr[CO(NH2)2]×100%=1.8 t×14×260×100%=0.84 t≈0.8 t
方法二：
Ar(N)×2Mr[CO(NH2)2]×100%=14×260×100%≈46.7%
1.8 t×46.7%≈0.8 t
答：可固定二氧化碳660 t，2 t该化肥中含氮元素0.8 t。
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