Potassium is a Group I element, so to get to a filled valence shell, it will lost one electron, yielding .

Arsenic is a Group 5 element, so it needs to gain three electrons to obtain a filled valence shell, yielding .

In order to balance out the charges, the resultant salt will be .

Potassium is a Group I element, so to get to a filled valence shell, it will lost one electron, yielding .

Arsenic is a Group 5 element, so it needs to gain three electrons to obtain a filled valence shell, yielding .

In order to balance out the charges, the resultant salt will be .

Combustion is the chemical reaction of a hydrocarbon with molecular oxygen, and it always produces carbon dioxide and water. Knowing the reactants and products, the unbalanced equation must be:

We start by balancing the hydrogens. Since there are 10 on the left and only 2 on the right, we put a coefficient of 5 on water.

Similarly, we balance carbons by putting a 4 on the carbon dioxide.

To find the number of oxygens on the right, we multiply the 4 coefficient by the 2 subscript on O (which gets us 8 oxygens) and then add the 5 oxygens from the 5 water molecules to get a total of 13. The needed coefficient for on the left would then have to be 13/2.

Because fractional coefficients are not allowed, we mutiply every coefficient by 2 to find our final reaction:

Combustion is the chemical reaction of a hydrocarbon with molecular oxygen, and it always produces carbon dioxide and water. Knowing the reactants and products, the unbalanced equation must be:

We start by balancing the hydrogens. Since there are 10 on the left and only 2 on the right, we put a coefficient of 5 on water.

Similarly, we balance carbons by putting a 4 on the carbon dioxide.

To find the number of oxygens on the right, we multiply the 4 coefficient by the 2 subscript on O (which gets us 8 oxygens) and then add the 5 oxygens from the 5 water molecules to get a total of 13. The needed coefficient for on the left would then have to be 13/2.

Because fractional coefficients are not allowed, we mutiply every coefficient by 2 to find our final reaction:

Only the calcium and carbonate ions are reacting according to the solubility rules to form calcium carbonate.

Only the calcium and carbonate ions are reacting according to the solubility rules to form calcium carbonate.

When writing/balancing a single replacement reaction, make sure to consult the activity series, because that will tell us if a reaction will actually take place. Remember to look at the cations (metals and hydrogen) and where they are in relation to each other on the activity series. The higher one on the activity series is the most reactive; so if the cation by itself is the most reactive, it will replace the other cation and a reaction will occur. Boyle's law explains the inverse relationship between volume and pressure with respect to certain amount of an ideal gas at constant temperature.

When writing/balancing a single replacement reaction, make sure to consult the activity series, because that will tell us if a reaction will actually take place. Remember to look at the cations (metals and hydrogen) and where they are in relation to each other on the activity series. The higher one on the activity series is the most reactive; so if the cation by itself is the most reactive, it will replace the other cation and a reaction will occur. Boyle's law explains the inverse relationship between volume and pressure with respect to certain amount of an ideal gas at constant temperature.

The best way to solve this problem is to try all the possible answers. When we try 8, means that there must be . means that there must be just , which means that there is . When is reduced to , there are 5 remaining electrons. So 8 is correct. Alternatively, this question may be answered by the classical "trial and error" method of balancing equations.

The best way to solve this problem is to try all the possible answers. When we try 8, means that there must be . means that there must be just , which means that there is . When is reduced to , there are 5 remaining electrons. So 8 is correct. Alternatively, this question may be answered by the classical "trial and error" method of balancing equations.