A photon has 8.0 × 10–15 J of energy. Planck’s constant is 6.63 × 10–34 J•s.
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In the titration of lemon juice, the presence of ascorbic acid means the concentration of citric acid you calculated is higher.
An acid-base titration is a common way to determine the unknown concentration of an acid, given we know the concentration of the base and determine the spent volume in the titration. Let's consider the neutralization reactions that take place in a mixture of citric acid and ascorbic acid.
Citric acid titration :
3 NaOH(aq) + H₃C₆H₅O₇(aq) → Na₃C₆H₅O₇(aq) + 3 H₂O(l)
Ascorbic acid titration:
NaOH(aq) + HC₆H₇O₆(aq) → NaC₆H₇O₆(aq) + H₂O(l)
If we titrated a solution that contained only citric acid, we can relate through stoichiometry the moles and concentration of citric acid. However, if the solution also contained ascorbic acid, we would have to spend more NaOH to titrate it. Since more NaOH would react, we would conclude that there is more citric acid to react, calculating a higher concentration of the same.
In the titration of lemon juice, the presence of ascorbic acid means the concentration of citric acid you calculated is higher.
You can learn more about titration here: brainly.com/question/2728613
Answer:
Q(total) = 283Kj
Explanation:
5 Heat Transitions …
Specific Heats => c(s) = 0.50cal/g∙⁰C, c(l) = 1.0 cal/g∙⁰C, c(g) = 0.48 cal/g∙⁰C
Phase Transition Constants => ΔHᵪ = Heat of Fusion = 80 cal/g; ΔHᵥ = Heat of Vaporization = 540cal/g
Note => Phase change regions => no temp. change occurs when 2 phases are in contact (melting and evaporation). Only when single phase substance exists (s, l or g) does temperature change occur. See heating curve for water diagram. The increasing slopes are temperature change regions and heat flow is given by Q =mcΔT. The horizontal slopes are phase changes ( melting & evaporation) and heat flow for each of those regions is given by Q = m·ΔH. Each transition energy is calculated individually (see below) and added to obtain the total heat flow needed.
Q = mcΔT for temperature change regions of the heating curve (single phase only)
Q = m∙ΔH for phase transition regions of the heating curve (2 phases in contact)
Solid (ice) => Melting Pt => Q(s) = mcΔT = (90.5g)(0.50cal/g∙⁰C)(11⁰C) = 478 cal
Melting (s/l) => Liquid (water) => Q(s/l) = m∙ΔHᵪ = (90.5g)(80cal/g) = 7240 cal
Liquid (water) => Boiling Pt => Q(l) = mcΔT = (90.5g)(1.0cal/g∙⁰C)(100⁰C) = 9050 cal
Boiling (l/g) => Gas (steam) => Q(l/g) = m∙ΔHᵥ = (90.5g)(540cal/g) = 48,870 cal
Gas (steam) => Steam @ 145⁰C => Q(g = mcΔT = (90.5g)(0.48cal/g∙⁰C)(45⁰C) = 2036 cal
Total Heat Transfer (Qᵤ) = Q(s) + Q(s/l) + Q(l) + Q(l/g) + Q(g)
= 478cal +7240cal + 9050 cal + 48,870cal + 2036cal
= 67,674 cal x 4.184 j/cal = 283,148 joules = 283 Kj
