Answer:
C₂H₅O₂
Explanation:
From the question given above, the following data were obtained:
Mass of compound = 0.25 g
Mass of CO₂ = 0.3664 g
Mass of H₂O = 0.15 g
Empirical formula =?
Next, we shall determine the mass of carbon, hydrogen and oxygen present in the compound. This can be obtained as follow:
For Carbon (C):
Mass of CO₂ = 0.3664 g
Molar mass of CO₂ = 12 + (2×16) = 44 g/mol
Mass of C = 12/44 × 0.3664
Mass of C = 0.1
For Hydrogen (H):
Mass of H₂O = 0.15 g
Molar mass of H₂O = (2×1) + 16 = 18 g/mol
Mass of H = 2/18 × 0.15
Mass of H = 0.02 g
For Oxygen (O):
Mass of C = 0.1 g
Mass of H = 0.02 g
Mass of compound = 0.25 g
Mass of O =?
Mass of O = (Mass of compound) – (Mass of C + Mass of H)
Mass of O = 0.25 – (0.1 + 0.02)
Mass of O = 0.25 –0.12
Mass of O = 0.13 g
Finally, we shall determine the empirical formula for the compound. This can be obtained as follow:
C = 0.1
H = 0.02
O = 0.13
Divide by their molar mass
C = 0.1 / 12 = 0.0083
H = 0.02 / 1 = 0.02
O = 0.13 / 16 = 0.0081
Divide by the smallest
C = 0.0083 / 0.0081 = 1
H = 0.02 / 0.0081 = 2.47
O = 0.008 / 0.008 = 1
Multiply by 2 to express in whole number
C = 1 × 2 = 2
H = 2.47 × 2 = 5
O = 1 × 2 = 2
Thus, the empirical formula for the compound is C₂H₅O₂
A heating curve graphically represents the phase transitions that a substance undergoes as heat is added to it. The plateaus on the curve mark the phase changes. The temperature remains constant during these phase transitions.
Answer:
3). Chemical potential energy
1). lower in charcoal than in coal.
Explanation:
Chemical potential energy is defined as the energy that can be absorbed or stored in a substance's chemical bonds. It can be released when there is a change in the number of particles of the substance.
As per the question, coal releases more heat than charcoal because 'the chemical potential energy of charcoal is lower than the coal' <u><em>and hence, the latter would release more heat on burning i.e. the energy that was absorbed in the chemical bonds of the substance</em></u>. Hence, option 3 and 1 are the correct answers.
