We have to add the both half cell equations and eliminate the number of electrons lost/gained.
<h3>What modification must Kim make to the equations?</h3>
The term redox reaction is a type of reaction that occurs when an electron is lost or gained in a reaction system. We can see that in this reaction, zinc looses two electron which are gained by copper.
If we want to obtain the equation 4.9 which is the overall equation of the redox reaction from the various half cell equations then we have to add the both half cell equations and eliminate the number of electrons lost/gained.
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It’s B. The kinetic molecular theory states that matter is made up of constantly moving particles.
Considering the definition of percentage by mass, the mass percentage of CaCO₃ is 68.59%.
<h3>What is mass percentage</h3>
The percentage by mass expresses the concentration and indicates the amount of mass of solute present in 100 grams of solution.
In other words, the percentage by mass of a component of the solution is defined as the ratio of the mass of the solute to the mass of the solution, expressed as a percentage.
The percentage by mass is calculated as the mass of the solute divided by the mass of the solution, the result of which is multiplied by 100 to give a percentage. This is:

<h3>Mass percentage of CaCO₃</h3>
In this case, you know:
- mass of CaCO₃: 2.62 grams
- mass of limestone: 3.82 grams
Replacing in the definition of mass percentage:

<u><em>mass percentage= 68.59 %</em></u>
Finally, the mass percentage of CaCO₃ is 68.59%.
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Answer:
10.1 g of Al are formed
Explanation:
The reaction is:
2AlCl3 --> 2Al + 3Cl2
So 2 moles of aluminun chloride decompose into 2 moles of Al and 3 moles of chlorine.
Ratio is 2:2.
Let's convert the mass of salt into moles (mass / molar mass)
50 g / 133.34 g/mol = 0.374 moles.
As the ratio is 2: 2, if I have 0.374 moles of salt, I would produce the same amount of Al, just 0.374.
Let's convert the moles to mass
(Mol . molar mass)
0.374 mol . 26.98 g / mol = 10.1 g of Al are formed
Ξ
Answer:
For pure substances, the mass and volume will always be the same or will always change the same way because all substance are the same throughout.
While for mixtures, you can have varying amount of each component therefore mass and volume will not change the same way for substances