CHM 105-001 Exam 1, Sp. 2014 Answer all the questions in order in the blue book.

Question

CHM 105-001 Exam 1, Sp. 2014 Answer all the questions in order in the blue book. Where appropriate you must show your calculations for full credit. 1. Answer all parts: a) what is the density of lead if a sample weighing 1 635 g has a volume of 1.5 mL (b) The density of Hg is 13,6 g/em'at 20.0 'C. Ifa sample of mercury weighs 15.35 g, what is the volume in em? And; (c) Why is it necessary to state the temperature in b) above? a) Give the no. of protons, electrons and neutrons in each of the following nuclides: 2. i) Mn-55 ii) Sr-90, and b) How many protons and electrons are in i) Cu 3. Answer all parts: a) Tell what is meant by the term isotopes; and b) Draw a 'Bohr atom' diagram for each of the 3 isotopes of hydrogen 4. Write the electronic configurations for each of the following elements (AI ()s (iii) Ca 5. Write the electronic configurations for each of the following ions: (0 Al (i)s (ii) Ca 6. Give the Lewis symbols for each of the following atoms: i) N (ii) Br (ii) Cs (iv) Ga 7. Draw the Lewis electron-dot structures for each the following molecules (a) HCI (b) NH, )CH. 8 Give the systemic name for each of the following compounds: (G) KI (ii) NH (ii) HNO iv) NaHCO

Explanation / Answer

(1)

(a)

Using relation:

Density = Mass/Volume

Putting values:

Density = 16.35/1.5 = 10.9 g/mL

(b)

Using relation:

Density = Mass/Volume

Putting values:

13.6 = 15.35/Volume

So,

Volume = 15.35/13.6 = 1.128 cm3

(c)

This is because density of mercury changes with temperature, and this is the principle upon which the mercury thermometers are based.

Hope this helps !

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