Answer:
Basically, a variable is any factor that can be controlled, changed, or measured in an experiment. It's anything that can be changed in the experiment.
Explanation:
Scientific experiments have several types of variables. The independent and dependent variables are the ones usually plotted on a chart or graph, but there are other types of variables you may encounter. The presence/absence of the chemical is the independent variable. The health of the (ex:)rat (whether it lives and can reproduce) is the dependent variable.
From the equation, we see that the molar ratio of Fe : S required is:
8 : 1
The moles of Fe present are: 9.42/56 = 0.168
Moles of S = 68/(32 * 8) = 0.265
The molar ratio is:
1 : 1.6
Therefore, iron is the limiting reactant as it is present in a ratio lower than that required. The ratio of
Fe : FeS is
1 : 1
So 0.168 moles of FeS will form. The mass of FeS will be:
Mass = 0.168 * (56 + 32)
Mass = 14.78 grams
14.78 grams of FeS will be formed.
Scientists use scientific notation to simplify numbers, basically. When dealing with really big numbers or really small numbers, the usage of scientific notation prevents them from having to write a bunch of zeroes.
Hope that helped you!