Answer:
The correct choices are:
- <em>using accurate measurements</em>
- <em>using pure chemicals</em>
- <em>performing the reaction under the most ideal conditions</em>
Explanation:
The theoretical yield is the maximum amount of product that could be obtained by the chemical reaction, from a given amount of reactants. You calculate the theoretical yield using the stoichiometry coefficients of the balanced chemical equation.
The <em>percent yield </em>is the ratio of the actual yield (the actual amount obtained) of a product to the theoretical yield for the same product, expressed as a percentage (i.e. multiplied by 100).
- percent yield = actual yield × 100 / theoretical yield
As the actual yield decrease (the numerator of the ratio), the percent yield decrease.
To increase the percent yield it is important:
- using accurate measurements
- performing the reaction under the most ideal conditions
<em><u>Using accurate measurements:</u></em> if you do not add the correct amounts of each reactant, then the product obtained will not be what you can predict from the theoretical calculations and you will be wasteing one or other reactant, without reaching the maximum yield possible.
<em><u>Using pure chemicals:</u></em> if the chemicals are not pure, the amount of actual reactants will be lower than they should be, leading to a lower actual yield.
<em><u>Performing the reaction under the most ideal conditions:</u></em> the actual rate of reactions depend on the conditions: temperature and pressure are the most commons. Since, temperature and pressure may change that rate of reactions, you should find and use the most ideal conditions to get the greatest actual yield.
<em>Adding water</em>, can just dilute the reactants and would decrease the rate of reaction, which would not be helpful to increase the yield.
Answer:
Physical change because even though gas formation was observed, the water was undergoing a state change, which means that its original properties are preserved.
Explanation:
Water boiling results in the physical state changing from solid to gaseous water. This moment can be called boiling or vaporizing, which is the change from liquid to gaseous state by heating water. Thus, the "Boiling Point" (PE) of a substance is the temperature at which that substance changes from liquid to gaseous state and, in the case of water, is 100 ° C. When the water reaches this temperature its physical change occurs because, despite the formation of gas, the water was undergoing a state change, which means that its original properties are preserved.
The answer is fusion. hope this helps!
Answer:
The number of atoms in the reactants equals the number of atoms in the products.
Explanation:
In every chemical reaction equation there are two sides; the reactants sides and the products side. The reactants side shows the species that combine to form the products. On both sides of the reaction equation, chemical species are found to be composed of atoms.
The major principle in balancing of chemical reaction equations is that the number of atoms of each element in the reactants side must be equal to the number of atoms of the same element on the products side. Once this condition is achieved, we can now say that the chemical equation is balanced.
