6.2 Balancing Equations

Question 1

What is a subscript number

Answer 1

A subscript is a number written slightly below the line in a chemical formula to show how many atoms of a particular element are present. Thus, in: H2SO4the 2 shows that there are 2 hydrogen atoms, the 4 shows there are 4 oxygen atoms. These atoms areattachedto each other to form one molecule.

Question 2

What are coefficient numbers

Answer 2

Coefficients are written in front of the formula. They indicate how many molecules or moles there are. Thus:

3 H2SO4tells us that we have 3 molecules of H2SO4(sulphuric acid), which areunattachedto each other

Question 3

What numbers can you change to balance an equation

Answer 3

While balancing an equation you can change the coefficients but never the subscripts

Question 4

What symbols represent the state of a compound or element

Answer 4

(s) = solid(l) = liquid(g) = gas(aq) = aqueous = dissolved in water

Question 5

What should you remember for balancing equations

Answer 5

Balancing is mainly trial and error remember:

1. NEVER change a subscript!
2. Change COEFFICIENTS only.
3. CHECK each element when you think you have the equation balanced.

Question 6

What are radicals, what can you do with them

Answer 6

Very often polyatomic groups (radicals), such as NH4+, SO4-2, and ClO3-1, remain together throughout the reaction. If so, they can be treated as a single unit in balancing. If the radical does change though you can’t treat it as a single unit

Question 7

What are fractional coefficients

Answer 7

It is sometimes easier to use fractional coefficients to balance equations, and then multiply the entire equation by 2 in order to get the smallest set of whole number coefficients.

Question 8

What order should you balance equations with oxygen carbon and hydrogen

Answer 8

C then H then O