Show all work.
Answer:
See below.
Explanation:
The mass of octane in the sample of gasoline is 0.02851 * 482.6 = 13.759 g of octane.
The balanced equation is:
2C8H18(l) + 25O2(g) ----> 16CO2(g) + 18H2O(g)
From the equation, using atomic masses:
228.29 g of octane forms 704 g of CO2 and 324.3 g of H2O
So the mass of CO2 formed from the combustion of 13.759 g of octane = (704 * 13.759) / 228.29
= 42.43 g of CO2.
Amount of water = 324.3 * 13.759) / 228.29
= 19.55 g of H2O.
Answer:
(a) Avoid parallax error
(b) To ensure that almost all the SCN⁻ has reacted.
Explanation:
(a) Avoiding bias
A Mohr pipet is a graduated pipet. To avoid bias, you should always hold the pipet so the meniscus is at eye level.
If your eye is above or below the meniscus, you will get an incorrect reading of the volume.
(b) Excess Fe³⁺
I am guessing that you are adding different volumes of SCN⁻ to Fe³⁺ to generate a Beer's Law plot of the concentration of FeSCN²⁺.
The problem is that the reaction is an equilibrium It does not go to completion.
Fe³⁺ + SCN⁻ ⇌ FeSCN²⁺
You use a large excess of Fe³⁺ to drive the position of equilibrium to the right and make sure that almost all the added SCN⁻ is converted to FeSCN²⁺.
Answer:
75mL
Explanation:
Data obtained from the question include:
C1 = 2M
V1 =?
C2 = 0.60M
V2 = 250mL
The original volume of solution can be obtained as follows:
C1V1 = C2V2
2 x V1 = 0.6 x 250
Divide both side by 2
V1 = (0.6 x 250) / 2
V1 = 75mL
The volume needed is 75mL