Zinc metal reacts with hydrochloric acid solution according to the reaction: zn(s) + 2 hcl(aq)  zncl2(aq) + h2(g). suppose 0.103 g of zn(s) is combined with 50.0 ml of hcl solution in a styrofoam cup calorimeter and all the zn(s) reacts. the temperature of the solution rises from 22.5 0 c to 23.7 0 c. the solution has a density of 1.0 g/ml and a specific heat capacity of 4.18 j/g- 0 c. a. find ∆hr for this reaction in units of kj/mol. b. what would be the work of the system in joules when one mole of zn reacts? c. what would be the work of the system in joules when 0.103 g of zn reacts?

Mass of Zn  = 0.103 g

Volume of HCl (V) = 50.0 ml

Density of solution (D) = 1.00 g/ml

Mass of HCl = D*V = 1.00 g/ml * 50.0 ml = 50.0 g

initial temp T1 = 22.5 C

Final temp T2 = 23.7 C

specific heat c = 4.18 J/g C

The heat (Q) required to raise the temp is given as:

Q = mcΔT = mc(T2-T1)

  = (0.103+50)g * 4.18 J/g C * (23.7-22.5) C = 251.3 J = 0.2513 kJ

To find ΔH in kJ/mol

# moles of Zn = mass of Zn/Atomic mass = 0.103/65.39 = 0.00158 moles

a) ΔH = 0.2513 kJ/0.00158 moles = 159.05 kJ/mol

b) A calorimeter is an isolated system where there is no exchange of heat/energy.

Work done is given as: W = PΔV

since ΔV = 0, as the volume remains constant

W = 0

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.