Answer:
The time taken for the cross mark to disappear decreases steadily down the column.
Explanation:
Now if we look at the data provided, we will discover that the volume of the HCl was held constant while the volume of the thiosulphate was increased steadily and the volume of water decreased steadily.
Recall that a system is more concentrated when it contains less volume of water and more volume of reactants. Hence as the volume of water in the system is being reduced, the concentration of reactants is increased.
It has been established that an increase in the concentration of reactants lead to an increase in the rate of reaction. The disappearance of the cross shows the completion of the reaction between HCl and thiosulphate. The faster or slower the cross disappears, the faster or slower the rate of reaction.
Since increase in concentration of reactants increases the rate of reaction, it is observed that as the volume of the thiosulphate increases (reactant concentration increases) the cross disappears faster (rate of reactant increases). Hence as the volume of thiosulphate increases, it takes a shorter time for the cross to disappear. This implies that the time column in the table (refer to the question) will decrease steadily as the volume of thiosulphate increases.
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
A I took the test already and it’s A for sure because the syrup has less water in it. It sucks the water out of the egg.
Answer:
The heat of formation = Heat of formation of the products - Heat of formation of the reactants
= -2323 + 104 = -2219 ≈ -2218.6 kJ/mol.
Explanation:
The law of conservation of energy states that the total energy is constant in any process. Energy may change in form or be transferred from one system to another, but the total remains the same
The heat of formation of C₃H₈ is 3C + 4 H₂ → C₃H₈ 
-104 kJ/mol
The heat of formation of O₂ is O₂ (g) → O₂ (g) 0 kJ/mol
The heat of formation of H₂O is H₂(g) + 1/2 O₂→ H₂O (g) -286kJ/mol
The heat of formation of CO₂ is C (s) + O₂ (g) → CO₂ (g) -393 kJ/mol
Therefore, in the given reaction we have;
C₃H₈ + 4 O₂ → 3 CO₂ + 4 H₂O
The heat of formation = Heat of formation of the products - Heat of formation of the reactants
The heat of formation = 3 × (-393) + 4 × (-286) - (-104) = -2219 ≈ -2218.6 kJ/mol.
