00:02
Hi there.
00:03
In this question, we have a few equations to write and balance.
00:08
So in the first one, we have propanol, which is c3h7 ohh, and is a liquid, and is combusting, which means it is burning in oxygen.
00:26
It's going to produce carbon dioxide, which is a gas, just like the oxygen was, and water vapor.
00:35
So also a gas.
00:40
Okay, so we need to balance this.
00:42
We see three carbons on the reactant side.
00:45
Remember balancing means that we're adding coefficients to get the same number of each type of atom on both sides of the arrow.
00:52
So three carbon, so i need a three in front of co2 to give me three carbon.
00:57
I see a total of eight hydrogen in the propanol, so i need a four in front of the h2o.
01:05
Now when i add up the oxygens, i have three times two, which is six, on the product side, plus four more oxygen in the water for a total of 10.
01:15
Well, i have one oxygen in the propanol.
01:20
So that means i need the rest, the 02 to equal 9.
01:25
The only way 02, a coefficient times 02 at equal 9, is if the coefficient were 9 halves.
01:34
Well, we know we cannot have a half as a coefficient.
01:39
But we also know a little trick that we can borrow from math class.
01:43
To get rid of a half, we can multiply by two as long as we multiply everything in the equation by two.
01:51
So that's what we're going to do.
01:53
This is balanced, but we have to get rid of that half there.
01:56
So i'm going to multiply each thing by two.
02:00
The previous coefficient in front of the propanol was a 1, so 2 times 1 gives me 2.
02:06
9 halves times 2 gives me 9.
02:11
3 times 2 in front of the co2 gives me 6.
02:16
And 4h2o, 4 times 2 is 8.
02:21
So now this equation is balanced.
02:25
We see it there are 6 carbon, 16 hydrogen on each side, and a total of 20 oxygen.
02:34
So that's now balanced.
02:36
So that is the final equation for that first reaction.
02:43
Right.
02:43
Next we have a double replacement reaction.
02:45
We have lead to nitrate.
02:49
So the two refers to the charge on the lead.
02:53
Nitrate has a negative one charge.
02:56
So i need two of those to write that formula correctly.
03:00
So that would be the lead to nitrate.
03:03
It is reacting with lithium phosphate.
03:06
Lithium has a one plus charge, while phosphate has a three negative charge.
03:12
So there needs to be three lithiums in the lithium phosphate.
03:18
This is a double displacement or double replacement reaction, which means the ions exchange places.
03:25
So we get lead phosphate, which is our solid.
03:28
Or the lead is positive 2.
03:31
Phosphate is 3 negative.
03:34
So this needs to be pb3, p .o4, 2.
03:40
So let the charges add up to 0 because 3 times 2 positive is 6 positive, and 2 times 3 negative is 6 negative...