Repeat trials multiple times
Answer:
C8H17N
Explanation:
Mass of the unknown compound = 5.024 mg
Mass of CO2 = 13.90 mg
Mass of H2O = 6.048 mg
Next, we shall determine the mass of carbon, hydrogen and nitrogen present in the compound. This is illustrated below:
For carbon, C:
Molar mass of CO2 = 12 + (2x16) = 44g/mol
Mass of C = 12/44 x 13.90 = 3.791 mg
For hydrogen, H:
Molar mass of H2O = (2x1) + 16 = 18g/mol
Mass of H = 2/18 x 6.048 = 0.672 mg
For nitrogen, N:
Mass N = mass of unknown – (mass of C + mass of H)
Mass of N = 5.024 – (3.791 + 0.672)
Mass of N = 0.561 mg
Now, we can obtain the empirical formula for the compound as follow:
C = 3.791 mg
H = 0.672 mg
N = 0.561 mg
Divide each by their molar mass
C = 3.791 / 12 = 0.316
H = 0.672 / 1 = 0.672
N = 0.561 / 14 = 0.040
Divide by the smallest
C = 0.316 / 0.04 = 8
H = 0.672 / 0.04 = 17
N = 0.040 / 0.04 = 1
Therefore, the empirical formula for the compound is C8H17N
They are all in forest climax means forest
Answer:
- <em><u>A physical change has occurred, with no energy change.</u></em>
Explanation:
When a pencil lead is broken there is not change of any chemical properties, therefore it is not a chemical change, but just a physical change. In this case the change is just the number of pieces and dimensions.
Chemical changes always involve the formation of new different substances; the bonds between the atoms of the starting substances (reactants) breake and new bonds are formed leading to new substances (products) with different chemical composition (arrange of atoms). Chemical changes occur through chemical reactions.
Hence, if there is not change on the chemical composition, you think on physical changes. Physical changes include change in shape, size, state of matter (e.g. solid, liquid, gas). In the case of a pencil lead breaking, it is a change in shape and size.
Also, since energy has not been absorbed or released during the change, the energy of the pencil lead before having been broken is equal to the sum of the energies of the pieces of pencil lead obtained. So, this is a physical change with no energy changes.
Some examples of physical changes that include change in energy are the change of state (e.g. solid to liquid or liquid to gas) and the dissolution of a compound.
