Answer:
The balanced equation is:
2NaCl + F₂ → 2NaF + Cl₂
Step-by-step explanation:
Balancing an equation is a bit like playing musical chairs. There is no quick formula for success, but a little trial and error will lead to the solution. And a little practice goes a long way.
NaCl + F₂ → NaF + Cl₂
Check how many times an element appears on each side of the equation:
Element Reactants Products Balanced?
Na 1 1 Yes
Cl 1 2 No
F 2 1 No
The equation has two elements not balanced. Lets start with the Cl. Each molecule of Cl2 has 2 Cl atoms, but there is only 1 brought in by the NaCl. We can't use Cl as a product, since it does not exist under normal conditions. So lets make the coefficient for the NaCl 2, instead of 1.
2NaCl + F₂ → NaF + Cl₂
Element Reactants Products Balanced?
Na 2 1 No
Cl 2 2 Yes
F 2 1 No
Now the sodium is unbalanced due to this change. Add a coefficient of 2 to the NaF to accomodate the extra sodium atom:
2NaCl + F₂ → 2NaF + Cl₂
Element Reactants Products Balanced?
Na 2 2 Yes
Cl 2 2 Yes
F 2 2 Yes
The equation is now balanced. Each atom can be accounted for.
2NaCl + F₂ → 2NaF + Cl₂
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This process may seem a bit tedius, but it becomes easier with practice: Some points that can help:
- Use pencil and paper. Be prepared to try/erase the options.
- Look for the most "difficult" or complex moplecule first and assign a coefficent of 1 just to get started. Each molecule must be a whole number in the final equation.
- Although the final equation needs to have whole numbers, there is nothing wrong with fractions to start the process. For the example above, instead of doubling the NaCl, add a (1/2) as the Cl2 coefficient:
NaCl + F₂ → NaF + (1/2)Cl₂
Element Reactants Products Balanced?
Na 1 1 Yes
Cl 1 2 Yes
F 2 1 No
Now do the same for the F2 on the reactant side:
NaCl + (1/2)F₂ → NaF + (1/2)Cl₂
Element Reactants Products Balanced?
Na 1 1 Yes
Cl 1 2 Yes
F 2 2 Yes
The equation is now balanced. But there is no such thng as 1/2 of a molecule (except, perhaps, in politics).
So multiply all the coefficients by a facor that makes them whole numbers. We can use 2, in this case.
2NaCl + 2(1/2)F₂ → 2NaF + 2(1/2)Cl₂
2NaCl + 1F₂ → 2NaF + 1Cl₂
This is the correct equation. The point is that a non-whole coefficient may be used to start, as long as they are all whole numbers at the conclusion.