Need help on how to balance equations. Here are a few of the problems.

First let me supply the w/s directions:

Predict the products of the reactions below. Then, write the balanced equation and clasify the reactions.

Here are examples of a few of the different kinds of equations I have to balance:

1. sodium + hydrogen

2. sulfuric acid + sodium hydroxide

3. hydrogen peroxide

4. zinc + hydrochloric acid

I really don't understand how any of this is done, so, an explaination of where any numbers or such comes from would be ideal.

In order to avoid memorizing thousands of equations, one tries to categorize equations into groups or types. You have several types here. I won't balance all of them or give products but I think I can get you started.

First look at the activity series in your text or on the internet. Here is a good one on the net.
http://en.wikipedia.org/wiki/Reactivity_series
Look where Na is on the series. Very high. That means high reactivity.
Na + H2 ==> NaH but I don't know if this reaction will go at room temperature or not.
H2SO4 + NaOH ==> acid + base gives a salt + water. A good type to remember.
H2O2 ==> a decomposition reaction. Forms O2 and H2O.
Zn + HCl ==> If the metal is ABOVE H in the activity series, then H2 gas + the salt is produced. If the metal is BELOW H in the activity series, there is no reaction. Another good type to remember.

Balancing chemical equations involves ensuring that the number of atoms of each element on both sides of the equation is equal. To do this, you need to follow several steps.

Let's go through each of the given examples one by one.

1. Sodium + Hydrogen

To predict the products, you need to be familiar with the reactivity of the elements involved. Sodium is an alkali metal, and it will react with hydrogen to form sodium hydride (NaH).

The balanced equation is: 2 Na + H2 -> 2 NaH

In this equation, there are 2 sodium atoms on the left side (2 Na), 2 hydrogen atoms on the right side (H2), and 2 sodium atoms and 2 hydrogen atoms on the product side (2 NaH). This equation is already balanced, as the number of atoms of each element is the same on both sides.

2. Sulfuric Acid + Sodium Hydroxide

In this case, you need to know the formulas of sulfuric acid (H2SO4) and sodium hydroxide (NaOH). The reaction between these two compounds results in the formation of water (H2O) and sodium sulfate (Na2SO4).

The balanced equation is: H2SO4 + 2 NaOH -> Na2SO4 + 2 H2O

In this equation, there are 2 hydrogen atoms and 4 oxygen atoms on the left side (H2SO4 and NaOH), 2 sodium atoms and 1 sulfur atom on the right side (Na2SO4), and 4 hydrogen atoms and 4 oxygen atoms on the product side (2 H2O). Each side of the equation has the same number of atoms for each element, so it is balanced.

3. Hydrogen Peroxide

Hydrogen peroxide (H2O2) can decompose into water (H2O) and oxygen gas (O2).

The balanced equation is: 2 H2O2 -> 2 H2O + O2

In this equation, there are 4 hydrogen atoms and 4 oxygen atoms on the left side (2 H2O2), 4 hydrogen atoms and 2 oxygen atoms on the right side (2 H2O), and 1 oxygen atom on the product side (O2). The equation is balanced since the number of atoms of each element is equal on both sides.

4. Zinc + Hydrochloric Acid

Zinc (Zn) reacts with hydrochloric acid (HCl) to form zinc chloride (ZnCl2) and hydrogen gas (H2).

The balanced equation is: Zn + 2 HCl -> ZnCl2 + H2

In this equation, there is 1 zinc atom on the left side (Zn), 2 hydrogen atoms and 1 chlorine atom on the right side (2 HCl), 1 zinc atom and 2 chlorine atoms on the product side (ZnCl2), and 2 hydrogen atoms on the product side (H2). The equation is balanced as the number of atoms of each element is the same on both sides.

To balance equations, you need to analyze the compounds and the numbers of each atom in them. Then adjust the coefficients (numbers in front of the compounds) to make sure that there is an equal number of atoms on both sides of the equation. Remember, never change the subscripts within a formula as it would change the compound itself.

I hope this explanation helps you understand how to balance chemical equations.