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Alright,so my Science 10 exam is comming up and although I'm decent in Chemistry, I always had trouble with balance chemical equations.

I get the concept that if there 2 more "X" on the Products side,you have to double up the "X" in the Reactans,but is there any actual technique to find out what number to add in? To be honest,when balancing equations I just use a "trial & error" technique.

TL;DR: Is there an actual technique to balance equations?

I usually write a column below each side of the reaction that has each element as well as its corresponding amount.

For example :
CH4 + O2 -> CO2 + H2O
C - 1_______C - 1
H - 4_______H - 2
O - 2_______O - 3

Then I would compare the two columns and look for a way to make the two sides equal. This is usually done with trial and error, but if you do enough of them it becomes second nature. In this example I would look at the hydrogen row and see that I'd need double the amount of hydrogens on the right side. Therefore, I would increase the number of H2Os to two and increase the numbers in the columns respectively.

CH4 + O2 -> CO2 + 2 H2O
C - 1_______C - 1
H - 4_______H - 4
O - 2_______O - 4

Now I have the C and H similar, but the O is not balanced. I need double the amount of O on the left side, so I would increase the number of O2 to two and increase the numbers in the columns respectively.

CH4 + 2 O2 -> CO2 + 2 H2O
C - 1_________C - 1
H - 4_________H - 4
O - 4_________O - 4

When the columns on both sides balance out, you are done.

Best tech: Start with halogens, than N, S, O, C, H. Basically start with the rare/less common one first, than move on to common ones like Carbon, than Hydrogen.

I can't remember 10th grade much, but probably just be simple reactions or combustion at best.

Carbon source + O2 -> CO2 + H2). Balance the Carbon in this case, than Oxygen, than Hydrogen. If it doesn't work, double your values by two and it should even out.

Surprisingly you'll still use this, not very often at all, but once in awhile. Working in Grad School and it pops up once in awhile.

Goseki wrote:Best tech: Start with halogens, than N, S, O, C, H. Basically start with the rare/less common one first, than move on to common ones like Carbon, than Hydrogen.

I can't remember 10th grade much, but probably just be simple reactions or combustion at best.

Carbon source + O2 -> CO2 + H2). Balance the Carbon in this case, than Oxygen, than Hydrogen. If it doesn't work, double your values by two and it should even out.

Surprisingly you'll still use this, not very often at all, but once in awhile. Working in Grad School and it pops up once in awhile.

Yeah those are easy. But I get a mindfuck when its Double Replacement I'll try chickenfather technique.

actually, there is way way to calculate it
we saw it in math class last year
Just can't.. remember... how... :s

If you've taken algebra, it's basically an equation from that.


I refuse to help any more than that, if that doesn't work, then do what you should do in the first place, ask your teacher.

It is not that hard to calculate it. You just have to see how the oxidation levels change. A simple example: Al+ O2 = Al2O3
At the beginning Al had a 0 ox. level, and so did the O2.
After the reaction, Al was +3, O2 -2.
So Al gave away 3 electrons, O2 bonded 2*2=4 electrons.
The equation is:
4 Al+3 O2 = 2Al2O3
Now that you have the main numbers the rest is easy. This was a very simple equation but the technique is the same for the longer equations too. Just find the elements which ox. level changed.

That shit is easy.
Does anyone wanna help me with Ionization and pH scale?
Was absent that day

I had a thread like this when I was in gr 10, search for it, it helped me a lot

!NEW!
online class in SRF!

Basically for pH problems, know the basic pH relationship. pH = -log [H+], pOH = -log [OH-], pH + pOH = pH2O. Than it's really just re-arranging stuff to get the answer.

For example, first question was H3PO4+, that's the acid/protonated form of phosphoric acid, H2PO4. So the [H] = [H3PO4]

Other questions, brief look just look like rearranging thsoe formulas to get the pH or concentration.

Squirt wrote:That shit is easy.
Does anyone wanna help me with Ionization and pH scale?
Was absent that day

Spoiler!

What is the Hydronium ion concentration and Hydroxide concentration for a solution of 0.0004M H3PO4?


A certain acid is diprotic. It has [ OH- ] of 1.4 x 10-9 M. What is the Molarity of this Acid. Provide a possible identity to this acid.


You dissolve 3.4 grams of Barium Hydroxide in enough water to make 450 ml of solution. Assuming that all the barium Hydroxide dissolves determine [ H3O+ ] and [ OH- ].


For problem #3 you now have the concentration of Hydronium and Hydroxide. Determine the pH and pOH for the Barium Hydroxide solution you made above.


Typical household ammonia has a [ OH- ] of 3 x 10-3 M. First determine the [ H3O+ ] concentration. Then determine the pH of household ammonia and tell if it is an acid or a base.


Calculate the pH and pOH of 0.026M HNO3.


Human blood has a [ OH- ] of 2.5 x10-7 M. Determine the pH for human blood.

GTFO my thread Nah,Im joking. My question is answered.

I don't know what science 10 means, but if there are redox reactions you have to balance then there are rules for that, differing depending on medium; just google it, it's like 2 rules with 4 steps each for acidic and basic soln. There are actually a lot of rules/shortcuts for balancing chemical equations harder than redox so they won't help; oh, and look up kinetics balancing rules if you have that too, think you learn that in high school.

SM-Count wrote:I don't know what science 10 means, but if there are redox reactions you have to balance then there are rules for that, differing depending on medium; just google it, it's like 2 rules with 4 steps each for acidic and basic soln. There are actually a lot of rules/shortcuts for balancing chemical equations harder than redox so they won't help; oh, and look up kinetics balancing rules if you have that too, think you learn that in high school.

Science 10 is Grade 10 Science. Then it splits into Chemistry 20(Gr.11) & Chemistry 30(Gr.12), Physics 20(Gr.11) & Physics 30(Gr.12), Biology 20(Gr.11) & Biology 30(Gr.12).

Good thing is that you can take a 30 course even if you're in Gr.11. Thats what I'll be doing next year,taking Bio 20 and Bio 30. By the end of High-School I'll have all the sciences,I'm so cool

i never used a certain written down process, just looked at it wrote it down step by step, nothing to hard, just takes a a little time

also in Bio 30, (our advanced Bio) we got to disect CATS!, roflcopter (4chan would RAGE )

Next year we get cats and pigs for ap bio!

Squirt wrote:Next year we get cats and pigs for ap bio!

lol AP.

In advanced anatomy we get to dissect cadavers.
(I'm not in the class, but I have friends that are or are going to be in that class next year.)