Write a hypothesis that answers the lesson question, “while observing a chemical reaction, how can you tell which reactant is limiting? ” hypothesis: if a substance is the limiting reactant, then . . because . .

If a substance is the limiting reactant, then it will be completely used by the time the reaction completes because it is the reactant that reacts completely and the reaction stops after it is completely used up.

Explanation:

Limiting reagent is a reagent as it limits the formation of product and Excess reagent is the reagent which is preset in excess.

For example: if 0.75 moles of HCl and 1.5 moles of magnesium are reacted together.

According to stoichiometry:

As 2 mole of reacts with 1 mole of

0.75 moles of will react with = of

is a limiting reagent as it limits the formation of product and Mg is an excess reagent as (1.5-0.38)=1.12 moles of magnesium are left unreacted.

it is the minimum amount of material needed to sustain a fission reaction.

critical mass is the minimum amount of fissionable material that must be assembled for a sustained fission reaction to take place. although two to three neutrons are produced for every fission, not all of these neutrons are available for continuing the fission reaction. if the conditions are such that the neutrons are lost at a faster rate than they are formed by fission, the chain reaction will not be self-sustaining.   at the point where the chain reaction can become self-sustaining, this is referred to as critical mass.