Question

What number should be substituted for the question mark to balance the equation?
2C2H6 +?O2 → 4CO2 + 6H2O + heat

A. 3.

B.7
C.5
D.4

Answer 1

make sure the total number of O atoms on both sides are equal. I count 4x2 O's in the \(CO_2\) and 6x1 O in the \(H_2O\), so how many O atoms is that total?

Answer 2

i dont know. im spastic and panicking right now, cant think

Answer 3

@JFraser

Answer 4

count the O atoms that are on the right side of the arrow.

Answer 5

there are 14 total

Answer 6

ok, on the left there are 2, without the substitute,right? @JFraser

Answer 7

that cant be right.

Answer 8

almost. the subscript tells you that each oxygen MOLECULE has 2 oxygen ATOMS

Answer 9

it's the total number of ATOMS that has to be the same on both sides.

Answer 10

what the difference between a number in front of the element symbol and behind it? thats the major thing that screwing me up.

Answer 11

@JFraser

Answer 12

the subscript after tells you how many of each atom make up one COPY of that molecule

Answer 13

the coefficient in front tells you how MANY COPIES of each molecule need to be used

Answer 14

still confused. @JFraser

Answer 15

im counting 12 atoms on the left. 2x2 +6 + 2

Answer 16

sorry if im frustrating you....

Answer 17

@Abhisar can you help me?

Answer 18

WHat are you not able to understand?

Answer 19

i know the answer is seven (something i cannot understand how i know) but i have no idea how the number is relevent to the situation

Answer 20

@Abhisar

Answer 21

alright then....

Answer 22

See it's very easy, while balancing you need to make sure that number of each atom is equal on both the left hand and right hand side...

Answer 23

Since, you know that the answer is 7. Let's check why it is so...

Answer 24

i've tried counting atoms on the left and keep getting 12 @Abhisar

Answer 25

Now let's see if we get 14 atoms on left hand side when we put 7 at the place of ?.

Is 7x2=14 ?

YEs...so we get 14 oxygen atoms by replacing ? with 7. Thus the answer is 7.

Getting it?

Answer 26

Let's first check how many oxygen atoms are there on the right hand side of the equation.

\(\sf 2C_2H_6 +?O_2=\boxed{4CO_2 + 6H_2O}\) + heat

Right hand side is the boxed part of the equation. There are 4X2=8 oxygen atoms from the \(\sf 2CO_2\) part and 6 oxygen from the \(\sf 6H_2O\) part. So total 8+6=14 oxygen atoms on right hand side...

Answer 27

2C2H6 + ?)O2...... i keep thinking 2x2 + 6 + 2 @Abhisar

Answer 28

I think the responses showed up in wrong order due to some reason....But is it clear now?

Answer 29

Counting number of oxygen after replacing ? with 7

Left hand side
\(\sf 7O_2\)
Number of oxygen = 7X2=14

Right hand side
\(\sf 4CO_2\)
Number of oxygen= 4X2=8
\(\sf 6H_2O\)
Number of oxygen= 6X1=6
Total on RHS=8+6=14

Answer 30

nvm i passed the test @Abhisar