Answer: Percent yield represents the ratio between what is experimentally obtained and what is theoretically calculated, multiplied by 100%.
% yield
=
actual yield
theoretical yield
⋅
100
%
So, let's say you want to do an experiment in the lab. You want to measure how much water is produced when 12.0 g of glucose (
C
6
H
12
O
6
) is burned with enough oxygen.
C
6
H
12
O
6
+
6
O
2
→
6
C
O
2
+
6
H
2
O
Since you have a
1
:
6
mole ratio between glucose and water, you can determine how much water you would get by
12.0
g glucose
⋅
1 mole glucose
180.0 g
⋅
6 moles of water
1 mole glucose
⋅
18.0 g
1 mole water
=
7.20
g
This represents your theoretical yield. If the percent yield is 100%, the actual yield will be equal to the theoretical yield. However, after you do the experiment you discover that only 6.50 g of water were produced.
Since less than what was calculated was actually produced, it means that the reaction's percent yield must be smaller than 100%. This is confirmed by
% yield
=
6.50 g
7.20 g
⋅
100
%
=
90.3
%
You can backtrack from here and find out how much glucose reacted
65.0 g of water
⋅
1 mole
18.0 g
⋅
1 mole glucose
6 moles water
⋅
180.0 g
1 mole glucose
=
10.8
g
So not all the glucose reacted, which means that oxygen was not sufficient for the reaction - it acted as a limiting reagent.
Explanation:
Answer:
ΔH = 200 kJ/mol
Explanation:
Step 1: Data given
activation energy (Ea) is: 450 kJ/mol
activation energy (Ea) of the reverse reaction is 250 kJ/mol
Step 2: The balanced equations
C4H10 ---> C2H6 + C2H4 Ea = 450 kJ/mol
C2H6 + C2H4 ---> C4H10 Ea = 250 kJ/mol
Step 3: Calculate ΔH
Since the reverse reaction has a lower activation energy, this means we need less reaction for the reverse reaction to happen. We can say the reaction absorbs energy, so this is the endothermic reaction.
Ea ( of the forward reaction) = ΔH + Ea (of the reverse reaction)
ΔH = Ea ( of the forward reaction) - Ea (of the reverse reaction)
ΔH = 450 kJ/mol - 250 kJ/mol
ΔH = 200 kJ/mol
Since the reactionis endothermi, ΔH is positive
A chemical symbol represent the number of an element
Answer:
half life would be the correct choice
Explanation:
