CHEM 101 Lab Exam Questions With
All Correct Answers
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
The spectrometer gets data on ________________ - ANSWER- absorption
The plot of _______________ against ___________________ of incident light is called
a spectrum - ANSWER- Absorption, wavelength
The shorter the wavelength the _____________ the energy - ANSWER- higher
Transitions with the smallest energy change will have the longest wavelength, explain
why this is? - ANSWER- This is because energy is inversely proportional to wavelength
What are the two posssible reasons for an object to show a particular colour? -
ANSWER- 1) THe absorbance of all wavelengths but those of said colour
2) THe absorbance of the complimentary colour
Why did the smarties show the colour they did? - ANSWER- Because they absorbed
the complimentary colour
What is the main ore of Al? What is it composed of? - ANSWER- The main ore of Al is
bauxite, a hydrate of Al2O3, mixed with oxides of iron, silicon, and titanium
What are the two ways you can recycle scrap aluminum? - ANSWER- By melting it or a
chemical reaction
Al(OH)3 is atmospheric, what does this mean? - ANSWER- It can react either with an
acid or with a base
, What does a fertilizer label of 10-20-20 means - ANSWER- The guaranteed percent
nitrogen, phosphoric acid, and potash in the fertilizer
What are the other products of the reaction that creates Cu(NO3)2? - ANSWER- NO
and H2O
On exposure to air, what happens to NO - ANSWER- It forms NO2 and becomes a
posonus reddish brown gas
What is the filtrate? - ANSWER- The liquid that passes through the filter into the filter
flask
Efflorescent - ANSWER- Hydrates that spontaneously lose water to the atmosphere
How does efflorescence occur? - ANSWER- This loss of water occurs because the
vapor pressure of water exerted by efflorescent solids is greater that that of the vapor
pressure of water in the surrounding atmosphere
Hygroscopic - ANSWER- Hydrates that spontaneously absorb water from the
atmosphere
Why may Hygroscopic hydrates, that spontaneously absorb water from the atmosphere,
be termed dessicates? - ANSWER- Because they are used a dry liquid/gas
Deliquescent - ANSWER- When a compound absorbs water from the atmosphere so
strongly that it dissolves in its own hydration
How do you go about removing water of crystilization from a hydrate that is stable at
room temperature? - ANSWER- It must be heated to a temperature at which the vapour
pressure of the water exerted by the solid hydrate exceeds the partial pressure of water
in the atmosphere above the solid
When all the water is gone from the hydrate, the compound is in its ________________
form - ANSWER- Anhydrous
As a hydrate is heated, and the water of hydration is driven off, the compound may
undergo one or more of the following changes? - ANSWER- 1) It may undergo a colour
change
2) The form of the crystal may change
3) It may dissolve in its own water of crysalization as the crystal structure breaks down
Why is vitamin C water soluble? - ANSWER- Due to the formation of hydroen bonds
between its (-OH) and (C=O) groups, and the (-OH) of the solvent molecules
Endpoint - ANSWER- A complete colour change occurs
All Correct Answers
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
The spectrometer gets data on ________________ - ANSWER- absorption
The plot of _______________ against ___________________ of incident light is called
a spectrum - ANSWER- Absorption, wavelength
The shorter the wavelength the _____________ the energy - ANSWER- higher
Transitions with the smallest energy change will have the longest wavelength, explain
why this is? - ANSWER- This is because energy is inversely proportional to wavelength
What are the two posssible reasons for an object to show a particular colour? -
ANSWER- 1) THe absorbance of all wavelengths but those of said colour
2) THe absorbance of the complimentary colour
Why did the smarties show the colour they did? - ANSWER- Because they absorbed
the complimentary colour
What is the main ore of Al? What is it composed of? - ANSWER- The main ore of Al is
bauxite, a hydrate of Al2O3, mixed with oxides of iron, silicon, and titanium
What are the two ways you can recycle scrap aluminum? - ANSWER- By melting it or a
chemical reaction
Al(OH)3 is atmospheric, what does this mean? - ANSWER- It can react either with an
acid or with a base
, What does a fertilizer label of 10-20-20 means - ANSWER- The guaranteed percent
nitrogen, phosphoric acid, and potash in the fertilizer
What are the other products of the reaction that creates Cu(NO3)2? - ANSWER- NO
and H2O
On exposure to air, what happens to NO - ANSWER- It forms NO2 and becomes a
posonus reddish brown gas
What is the filtrate? - ANSWER- The liquid that passes through the filter into the filter
flask
Efflorescent - ANSWER- Hydrates that spontaneously lose water to the atmosphere
How does efflorescence occur? - ANSWER- This loss of water occurs because the
vapor pressure of water exerted by efflorescent solids is greater that that of the vapor
pressure of water in the surrounding atmosphere
Hygroscopic - ANSWER- Hydrates that spontaneously absorb water from the
atmosphere
Why may Hygroscopic hydrates, that spontaneously absorb water from the atmosphere,
be termed dessicates? - ANSWER- Because they are used a dry liquid/gas
Deliquescent - ANSWER- When a compound absorbs water from the atmosphere so
strongly that it dissolves in its own hydration
How do you go about removing water of crystilization from a hydrate that is stable at
room temperature? - ANSWER- It must be heated to a temperature at which the vapour
pressure of the water exerted by the solid hydrate exceeds the partial pressure of water
in the atmosphere above the solid
When all the water is gone from the hydrate, the compound is in its ________________
form - ANSWER- Anhydrous
As a hydrate is heated, and the water of hydration is driven off, the compound may
undergo one or more of the following changes? - ANSWER- 1) It may undergo a colour
change
2) The form of the crystal may change
3) It may dissolve in its own water of crysalization as the crystal structure breaks down
Why is vitamin C water soluble? - ANSWER- Due to the formation of hydroen bonds
between its (-OH) and (C=O) groups, and the (-OH) of the solvent molecules
Endpoint - ANSWER- A complete colour change occurs
