Peds Ch 12
EE. about school performance and grades.
FF. why school is so distressing.
GG. to name one or two friends.
HH. whether bullying is taking place.
Lactic acid (abbreviated to HLac) is the acid found in sour milk products such as sour cream, cottage cheese, and yoghurt. Lactic acid has a molar mass of 90 g/mol. It is water soluble and as an acid will react with NaOH solution in the following way:
A student decided to test the amount of lactic acid in a sample of unsweetened yoghurt. She dissolved 100 grams of yoghurt in distilled water in a 250 mL volumetric flask. She then titrated 25 mL samples of the solution with 0.025 mol/L NaOH. The volumes of NaOH used (excluding the initial) were 20.1 mL,20.2 mL,20.0 mL,20.0 mL, and 20.2 mL.
(a) Calculate the moles (n(HLac)) of lactic acid in the 250 mL flask:
(b) Calculate the mass and percentage of lactic acid in the 100 g sample of yoghurt:
A radiator made out of iron of specific heat capacity
has a mass of 45.0 kg and is filled with 23.0 kg of water of specific heat capacity
. a. Determine the energy required to raise the temperature of the radiator–water system by 1 K. b. If energy is provided to the radiator at the rate of 450 W, calculate how long it will take for the temperature to increase by