Test+Questions

=__**Test Questions:**__= FOR TOMORROW'S THERMODYNAMICS TEST: Here are some calorimetry problem's you might like to try. Solutions (full) are accessible by clicking here: []

1. Phileas Fogg, the character who went around the world in 80 days, was very fussy about his bathwater temperature. It had to be exactly 38.0o C. You are his butler, and one morning while checking his bath temperature, you notice that it’s 42.0oC. You plan to cool the 100.0 kg of water to the desired temperature by adding an aluminum- duckie originally at freezer temperature (-24.0oC). Of what mass should the Al- duckie be? [Specific heat of Al = 0.900 J /( goC ); density of water =1 .00 g/ml]. Assume that no heat is lost to the air.

2. A certain material’s( environment) temperature increases by 1.0oC for every 1560 J that it gains. A 0.1964 g sample of quinone (molar mass = 108.1 g/mole) was burnt, and the surrounding material’s temperature increased from 20.3 oC to 23.5 o C. Find the molar heat of combustion for quinone.

3. A 1.55 g of CH4O sample is burnt in a calorimeter. If the molar heat of combustion of CH4O is -725 kJ/mole, and assuming that the 2.0 L of water absorbed all of the heat of combustion, what temperature change did the water experience?

4. 0.20 moles of HX were neutralized by NaOH. The concentrations of the base and acid were equal. If the temperature of the water in the calorimeter increased from 19.9 to 24.6 C, what was the original concentration of HX? //Molar heat of neutralization = -80 kJ/mole of HX//

5. In real calorimeters, most of the heat released by the bomb is absorbed by water, but a certain amount is also absorbed by the metal and insulation surrounding the water tank. A certain calorimeter absorbs 24 J/ oC. If 50.0 g of 52.7oC water is mixed with the calorimeter’s original 50.0 g of 22.3oC water, what will be the final temperature of the mixture?

Please have discussions based on the test tomorrow on the discussion tab. Ask questions and hopefully someone in the class or Leslie will be able to answer your question.

Hey guys ! Jennice here....I asked Leslie some of the questions we were having trouble with so please refer to the answers below before posting your questions..... Here are the some of the answers

Hi, It's JennA. I posted a summary of the definitions, from the concept map, in the notes section...

__ Grade 12 Chemistry Problem set:Atomic structure Chapter 3 __

Q6) What are the possible combinations of the 4 quantum numbers for an electron in the 4d subshell? n=4 l=0,1,2,3 However since we are only concerned about the 4d subshell, the value of l that we take into account is 2 (0=s orbital ,1= p orbital,2=d orbital) So taking into consideration the values of ml for only the d subshell ,or l =2 we get ml = 0,-1,+1,-2,+2 ms= 1/2 ,-1/2 Hence our 10 possible combinations are: 4,2,0,1/2 ; 4,2,0,-1/2; 4,2,1,1/2; 4,2,1,-1/2; 4,2,-1,1/2; 4,2,-1,-1/2; 4,2,2,1/2 ; 4,2,2,-1/2; 4,2,-2,1/2 ; 4,2,-2,-1/2
 * __Answer__** : There are ten possible combinations

Q7) In what ways do the spatial distribution of the orbitals in each pair differ from each other? Answer a) 1s and 2s -they are the same shape but different in energy levels (2s ia larger than 1s) b) 2s and 2p - 2s is spherical in shape, 2p is in the shape of an infinity sign c) 2px and 2py –same energy level and orbital shape but they have different orientations (x axis ,y axis)


 * __ NOTE __**: An orbital box diagram looks like this

Q17) Explain why the first ionization energy for copper is higher than that for potassium,whereas the second ionization energies are in the reverse order? Cu -1s2,2s2,2p6,3s2,3p6,4s1,3d10 K-1s2,2s2,2p6,3s2,3p6,4s1 The first ionization energy of copper is higher than that of potassium because potassium is in the first group of alkali metals ,hence it gives up it’s electrons very easily as compared to copper ,so even though we are removing electrons for both the element from 4s1 orbital their ionization energies differ. When we remove an electron from K,it gains a noble gas like configuration with a full p orbital and hence it’s second ionization energy is much higher than the it's first and also why it is higher than the second ionization energy of copper.

Q7) What holds nuclei together in an ionic bond ? ---electrostatic forces of attraction
 * __ Grade 12 Chemistry Problem Set 2B Atomic Theory __**

Q8)What holds nuclei together in a covalent bond?--- Forces of attraction between the nuclei and the electrons of the other atoms.

Q17) Arrange the following in order of greatest to weakest forces of attraction Dipole-dipole, hydrogen bonds, covalent bonds, London forces

**__ Answer : __** Covalent (network) bonds, hydrogen bonds, dipole-dipole, London forces

Q25)Rank the following from highest to lowest in terms of boiling point H2O,H2S,CO2,Fe,NaCl,SiO4

**__ Answer __** : NaCl ,Fe, H2O, H2S, SiO4, CO2