The electrons in an atom tend to assume the arrangement that gives the atom the least possible energy

Explain your reasoning to why the rusting of iron is a chemical change (evidence not needed but may add it)

Tju [1.3M]

When an iron object is left in damp air for a considerable time, it gets covered with a reddish- brown flaky substance called rust. ... Rusting of iron is a chemical change because a new substance iron oxide is formed. The presence of oxygen and water or water vapour is essential for rusting.

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3 years ago

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Most fertilizers consist of nitrogen-containing compounds such as NH3,CO(NH2)2,NH4NO3, and (NH4)2SO4. Plants use the nitrogen co

Y_Kistochka [10]

Answer: 1. $NH_3=82.4\%$

2. $CO(NH_2)_2=46.7\%$

3. . $NH_4NO_3=35\%$

4. $(NH_4)_2SO_4=21.2\%$

$NH_3$ has highest nitrogen content.

Explanation:

To calculate the mass percent of element in a given compound, we use the formula:

$\text{Mass percent of nitrogen}=\frac{\text{Mass of nitrogen}}{\text{Molar mass of nitrogen compound}}\times 100$

1. $NH_3$

$\text{Mass percent of nitrogen}=\frac{\text{Mass of nitrogen}}{\text{Mass of} NH_3}=\frac{14}{17}\times 100=82.4\%$

2. $CO(NH_2)_2$

$\text{Mass percent of nitrogen}=\frac{\text{Mass of nitrogen}}{\text{Mass of} CO(NH_2)_2}=\frac{14\times 2}{12\times 1+16\times 1+2\times 14+4\times 1}\times 100=\frac{28}{60}\times 100=46.7\%$

3. $NH_4NO_3$

$\text{Mass percent of nitrogen}=\frac{\text{Mass of nitrogen}}{\text{Mass of} NH_4NO_3}=\frac{14\times 2}{14\times 2+16\times 3+4\times 1}\times 100=\frac{28}{80}\times 100=35\%$

4. $(NH_4)_2SO_4$

$\text{Mass percent of nitrogen}=\frac{\text{Mass of nitrogen}}{\text{Mass of}(NH_4)_2SO_4}=\frac{14\times 2}{14\times 2+16\times 4+32\times 1+8\times 1}\times 100=\frac{28}{132}\times 100=21.2\%$