根据下列要求，写出有关反应的化学方程式：
（1）纯碱制取烧碱______；
（2）湿法炼铜______；
（3）常温下用混合物制氧气的分解反应______；
（4）葡萄糖的代谢______．
（1）纯碱制取烧碱：纯碱为碳酸钠，烧碱为氢氧化钠，故Na2CO3+Ca（OH）2═CaCO3↓+2NaOH；
（2）湿法炼铜：在溶液中发生的置换反应，Fe+CuSO4═FeSO4+Cu；
（3）常温下用混合物制氧气的分解反应：符合条件的为过氧化氢溶液分解反应：2H2O2
2H2O+O2↑； MnO2 .
（4）葡萄糖的代谢：葡萄糖的氧化反应：C6H12O6+6O2
6H2O+6CO2 酶 .
故答为：（1）Na2CO3+Ca（OH）2═CaCO3↓+2NaOH；
（2）Fe+CuSO4═FeSO4+Cu；
（3）2H2O2
2H2O+O2↑； MnO2 .
（4）C6H12O6+6O2
6H2O+6CO2 酶 .
| Modem cowboy seem to be giving up the bandanna (印花大手帕) handkerchief; yet there was a time when this article was almost as necessary to a cowboy’s equipment as a rope, and it served for purposes almost as varied. The bandanna made a good sling for a broken arm; it made a good bandage for a blood wound. Early Irish settlers on the Nueces River used to believe that a bandanna handkerchief that had been worn by a drowned man would, if cast into a stream above the sunken body, float until it came over the body and then sink, thus locating the body. Many a cowboy out on the lonely plains has been buried with a clean bandanna spread over his face to keep the dirt, or the coarse blanket on which the dirt was poured, from touching him. The bandanna has been used to hang men. Rustlers used to "wave" strangers around with it as a warning against nearer approach, though the hat was more commonly used for signaling. Like the Mexican sombrero (阔边帽) or the fourgallon Stetson, the bandanna could not be made too large. When the cowboys of the Old West make their final parade on the grassy shores of Paradise, the guidon (旗手) that leads them should be a bandanna handkerchief. It deserves to be called the "flag of the range country". |
The author implies that a cowboy was buried with a bandanna over his face ______.
A．as a token of respect for the dead
B．because of the bandanna’s magical powers
C．to provide a means of identification
D．because his religion demanded it