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3 years ago

What does the law of conservation of matter/mass state

2 answers:

8 0

The law of conservation of mass states that mass cannot be created or destroyed. It can only be transformed/transferred from one form to another.

Ivanshal [37]3 years ago

8 0

It states that mass in an isolated system is neither created or destroyed by chemical reactions or physical transformations.

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When a radioactive sample decays for 2 half-lives the amount remaining will be ____ of the original?

mash [69]

1/4 of the original.

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3 years ago

Mercury has an atomic number of 80 and a mass number of 200.

denis23 [38]

C. The mass number is the amount of Protons and electrons there are combined, so 200 - 80 is 120.

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4 years ago

Read 2 more answers

Following the Napoleonic Wars , the congress of vienna took steps meant to:

Slav-nsk [51]

Answer:

Prevent any European country from growing much stronger than its neighbors.

Explanation:

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3 years ago

Classify each of the following as a physical or a chemical change. Give

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Answer:

a is a physical changes

b is physical changes

c is a Chemical change

d is a physical changes

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3 years ago

Which of the following you is true for a limiting reactant

skad [1K]

Answer:

C) The limiting reactant has the lowest ratio of moles available / coefficient in the balanced equation.

Explanation:

Please, find attached a complete question to determine which of the statements is or are true for a limiting reactant in a chemical equation.

First, remember that the limiting reactant is the substance that is consumed completely while the excess reactant is the substance that does not react completely.

The limiting reactant is found comparing the stoichiometry ratio and the actual ratio between the reactants.

The stoichiometry ratio is found using the coefficientes of the chemical equation.

For illustration, assume the general chemical equation:

$aA+bB\rightarrow cC+dD$

The stoichiometric ratio of the reactants is:

$a\text{ }moles\text{ }of\text{ }A/b\text{ }moles\text{ }of\text{ }B$

If the ratio of the available moles of substance A to the available moles of substance B is greater than the stoichiometric ratio, it means that there are more moles of the substance A than what is needed to react with the available moles of substance B, then A will be in excess and B will B the limiting reactant.

If, on the contrary, the ratio of the available moles of substance A to the available moles of substance B is is less than the stoichiometric ratio, then substance A is less than the necessary to make the all the moles of substance B react, meaning that the substance A will limit the reaction (it will be consumed completely), while the substance B will be in excess.

As for the options:

A) The limiting reactant is has the lowest coefficient in a balanced equation.

This is false, since it is not the magnitude of the coefficiente what determines the limiting reactant, but the comparison of the ratios.

B) The limiting reactant is the reactant for which you have the fewest number of moles.

This is false because it is not the number of moles what determines the limiting reactant , but the comparison of the ratios.

C) The limiting reactant has the lowest ratio of moles available / coefficient in the balanced equation.

This is true as proved below.

The stoichiometric ratio of the reactants is:

$a\text{ }moles\text{ }of\text{ }A/b\text{ }moles\text{ }of\text{ }B$

The actual ratio is:

$available\text{ }moles\text{ }of\text{ }A/available\text{ }moles\text{ }of\text{ }B$

Assume the first ratio is less than the second (which describes when the substance A is in excess and the limiting reactant is the substance B).

$a\text{ }moles\text{ }of\text{ }A/b\text{ }moles\text{ }of\text{ }B$

Change the relation to show the ratios of moles available of each substance to the cofficient in the chemical equation:

$available\text{ }moles\text{ }of\text{ }B/b\text{ }moles\text{ }of\text{ }B$

Then, in the scenary that the limiting reactant is the substance B, the ratio of the left is lower than the ratio of the right, which is the same that limiting reactant has the lowest ratio of moles available / coefficient in the balanced equation.

D) The limiting reactant has the lowest ratio of coefficients in the balanced eqution/moles available.

This ratio is the inverse of the ratio of the previous statement, thus the relation is inverse, and, since the previous statement was true, this statement is false.

3 0

3 years ago