Answer:
7.46 g.
Explanation:
- Firstly, we need to calculate the amount of heat needed to warm 5.64 kg of water from 21.0°C to 70.0°C using the relation:
<em>Q = m.c.ΔT,</em>
where, Q is the amount of heat absorbed by water (Q = ??? J).
m is the mass of water <u><em>(m: we will determine).</em></u>
c is the specific heat capacity of water (c = 4.186 J/g.°C).
ΔT is the temperature difference (final T - initial T) (ΔT = 70.0 °C - 21.0 °C = 49.0 °C).
- To determine the mass of 1.76 L of water we can use the relation:
mass = density x volume.
density of water = 1000 g/L & V = 1.76 L.
∴ mass = density x volume = (1000 g/L)(1.76 L) = 1760.0 g.
∵ Q = m.c.ΔT
<em>∴ Q = m.c.ΔT </em>= (1760.0 g)(4.186 J/g.°C)(49.0 °C) = 360483.2 J ≅ 360.4832 kJ.
- As mentioned in the problem the molar heat of combustion of hexane is - 4163.0 kJ/mol.
<em>Using cross multiplication we can get the no. of moles of hexane that are needed to be burned to release 360.4832 kJ:</em>
Combustion of 1.0 mole of methane releases → - 4163.0 kJ.
Combustion of ??? mole of methane releases → - 360.4832 kJ.
∴ The no. of moles of hexane that are needed to be burned to release 360.4832 kJ = (- 360.4832 kJ)(1.0 mol)/(- 4163.0 kJ) = 0.0866 mol.
- Now, we can get the mass of hexane that must be burned to warm 1.76 L of water from 21.0°C to 70.0°C:
<em>∴ mass = (no. of moles needed)(molar mass of hexane)</em> = (0.0866 mol)(86.18 g/mol) = <em>7.46 g.</em>
Answer:
Molecular Formula => (CH₂)₇ => C₇H₁₄
Explanation:
Empirical ratio is calculated from the sequence...
%/100wt => grams/100wt => moles => mole ratio => reduce mole ratio => Empirical Ratio
C: 85.7% => 85.7g => (85.7/12)mol = 7.14 mole
H: 14.3% => 14.3g => (14.3/1)mol = 14.3 mole
C:H mole ratio => 7.14:14.3
Reduced mole ratio (divide by the smaller mole value) => (7.14/7.14):(14.3/7.14) => Empirical Ratio => 1:2 => Empirical Formula => CH₂
Molecular Wt = Whole No. Multiple of Empirical Formula Wt.
M.Wt = N(Emp Wt) => 98g = N(14g) => N = 7
∴Molecular Formula => (CH₂)₇ => C₇H₁₄
Question 4: C
question 5: D
I think the form energy that is found in the ice cubes would be thermal energy. It <span> is the </span>energy<span> that comes from heat. Since all things tend to go towards equilibrium, the ice cubes dissipates heat to equilibriate with the environment.</span>
Answer:
2.2%
Explanation:
Percentage error,
You apply the formula,
[(Estimated value - Actual value)/Actual value] × 100%
; [(43.26 - 42.32)/42.32] × 100
; (0.94/42.32) × 100
; 0.022 × 100
Percent error = 2.2%
