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:
(d) All spontaneous reactions have a negative free-energy change
Explanation:
All spontaneous reactions releases free energy which can be used later for the work to be done. A reaction with a negative value for ΔG releases free energy and is thus spontaneous
Heterogeneous 'mixtures' (because they don't meet the definition of mixtures) are mixtures substances that aren't completely uniformly spread out. They haven't reacted with the solvent to become a solution.
Explanation: There are 2 types of heterogeneous solutions, A Colloid and a suspension.
Colloid: You can check if a mixture is heterogeneous by passing a light ray through it. This may cause the Tyndall effect (If the mixture is a colloid) when the Colloidal Heterogeneous mixture's particles are so small that they refract the beam of light and the path of light will be visible, like if you add 3 drops of milk in a glass of Water and shine a laser light through it. This is because the particles are too small to be seen by the unaided eye but big enough to scatter you laser light. However that particles won't settle down or will be separated by a filter paper due to particles' small size.
Suspension: A solution will be a solution when the particles of the Mixture is big enough to be seen by the unaided eye. Like if you mix sand and Water, the sand will eventually settle down due to Gravity. The mixture's solute will be big enough to pass through a filter paper.
