CHEM 101 Lab Exam Questions and Answers All Correct
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Course
CHEM 101
Institution
CHEM 101
CHEM 101 Lab Exam Questions and Answers All Correct
When titrating vitamin C with KIO3 (Iodate), the following steps occur (once KI and HCl are added) - Answer-1) The iodate anion reacts with I- and H+ to form I2
2) Once formed, I2 is reduced immediately by vitamin C back to I-. As each I2 react...
CHEM 101 Lab Exam Questions
and Answers All Correct
When titrating vitamin C with KIO3 (Iodate), the following steps occur (once KI and HCl
are added) - Answer-1) The iodate anion reacts with I- and H+ to form I2
2) Once formed, I2 is reduced immediately by vitamin C back to I-. As each I2 reacts
with one C6H8O6, each IO3- that is added results in the reaction of 3 C6H8O6
molecules
3) After all of the vitamin C in the sample has been consumed, the I2 from the addition
of more iodate reacts rapidly with I- to form the linear triiodide ion, I3-
4) I3- will react promptly with starch to form the black-blue starch triiodide ion complex
When titrating vitamin C with KIO3, each IO3- that is added forms _____ I2 - Answer-3
Vitamin C reacts in a __:__ mole ratio with NaOH - Answer-1:1
The reaction of vitamin C with iodate is specific to the ______________ part of the
vitamin C molecule - Answer-ascorbate
The reaction of vitamin C with NaOH will take place with??? - Answer-Any sufficiently
acidic protons of any acid present
Each vitamin C reacts with _______ OH according to this experiment - Answer-1
The titration with KIO3 tells us what in comparison to the titration with NaOH? - Answer-
It tells us the moles of vitamin C present, whereas the titration with NaOH tells us the
moles of any acidic proton being present. So if they are similar you know that vitamin C
is the only acid, but if NaOH is higher (than 5%) you know there is another acid present
Buret readings should be done to ____________ mL - Answer-0.01
True or False: For colourless solutions you must use a buret reading card - Answer-
True
Do you read the bottom or the top of the meniscus? - Answer-Bottom
Heat Capacity (C) - Answer-The heat capacity of an object or substance is the amount
of heat needed to change its temperature per degree
True or False: A system contains internal energy; it does not contain heat or work -
Answer-True
, Which of C, c, and Cm are extensive properties? - Answer-C
Which of C, c, Cm are intensive properties? - Answer-c, Cm
What is c? - Answer-The specific heat capacity
What is Cm? - Answer-The molar heat capacity
How is C calculated using specific heat capacity (c)? - Answer-C = c * mass of
substance
How is C calculated using molar heat capacity (Cm)? - Answer-C = Cm * moles of
substance
Why is the energy transferred (heat) equal to the enthalpy change (delta H)? - Answer-
Because the calorimeter is at constant pressure
What equation relates heat capacity and enthaply change? - Answer-(Delta H)/(Tf-Ti)
True or False: The total enthalpy of the calorimeter plus contents is unchanged during
your experiment, thus deltaH = 0 - Answer-True. This is because the calorimeter is
designed to be an excelled thermal insulator
Delta H is negative if energy ___________ the block - Answer-leaves
Is experiment G endothermic or exothermic? - Answer-Endothermic
The enthalpy changes of chemical reactions are measured in a device called a
___________________ - Answer-Calorimeter
True or False: After the maximum temperature change is reached, the temperature will
change with time back towards Ti - Answer-True
What type of spectrum is emitted by gaseous discharge tubes? - Answer-A
discontinuous spectrum
White light from the sun emits what type of spectrum? - Answer-A continuous spectrum
from red to violet
How are photons emitted in discharge tubes? - Answer-As the excited atom returns to a
lower energy state, photons are emitted
What are 3 common applications of light emission by elements? - Answer-1) The flame
test
2) Fireworks
3) Office fluorecent lights
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