1. Given that 50 grams of ice is heated at -20.0 °C to steam at 135.0 °C.
i. Show the graph of the changes from ice to steam
ii. Calculate the energy needed to change the ice to steam
Please use these values:
Heat of fusion = 334.16 J g¯1
Heat of vaporization = 2259 J g¯1
specific heat capacity for solid water (ice) = 2.06 J g¯1 K¯1
specific heat capacity for liquid water = 4.184 J g¯1 K¯1
specific heat capacity for gaseous water (steam) = 2.02 J g¯1K¯1
2. The voltage of an electrochemical cell depends on the redox reaction occurring in the cell. Given a redox reaction below:
Zn(s) + Pb2+(aq) --> Zn2+(aq) + Pb(s)
Pb2+(aq) + 2 e--->Pb(s)Eº = -0.13V
Zn2+(aq) + 2 e--->Zn(s)Eº = -0.76V
Calculate the E.M.F (Voltage) of the cell
3. For the reaction between Cu and Sn the potentials are given below;
Cu2+(aq) +2e- -----------> Cu(s) Eºcathode = 0.34 (half-cell potential)
Sn(s) -----------> Sn2+(aq) + 2 e- Eºanode = - 0.14 (half-cell potential)
Calculate the E.M.F (Voltage) of the cell
4. Calculate pH given [H+] = 1.4 x 10-5 M
5. Find [H+] if pH = 8.5
6. Given the equation below, how many moles of each reactant were there if 13.7 moles of N2(g) is produced?
4NH3(g) + 6NO(g)→5N2(g) + 6H2O(g) 7.
8. Given the equation below, if 3.87×1023 particles of Sb2S3(s) are reacted with excess Fe(s), what mass of FeS(s) is produced?
Sb2S3(s) + 3Fe(s)→2Sb(s) +3FeS(s)
9. Given the following Unknown atoms with their respective atomic numbers,
X; Atomic number 19,
Y; Atomic number 15,
a. Deduce the identities of the elements X and Y.
b. What are the mass numbers of the two elements X and Y?
c. Calculate the number of Neutrons in the respective elements X and Y
d. Deduce the number of electrons in the respective elements X and Y
e. Give the electronic configurations of the two elements
1. Graph of the changes from ice to steam:
To create the graph, we need to represent the different stages of the phase change from ice to steam.
- First, plot a point at -20°C to represent the initial temperature of the ice.
- Then, draw a straight line with a positive slope to depict the heat absorption during the heating process from -20°C to 0°C. The slope represents the specific heat capacity of ice (2.06 J g^(-1) K^(-1)).
- At 0°C, draw a horizontal line to represent the phase change from ice to water. This line represents the heat of fusion, which is 334.16 J g^(-1). The temperature stays constant at 0°C during this phase change.
- After that, draw another straight line with a positive slope from 0°C to 100°C to represent the heating process from water to steam. The slope of this line represents the specific heat capacity of liquid water (4.184 J g^(-1) K^(-1)).
- At 100°C, draw another horizontal line to represent the phase change from water to steam. This line represents the heat of vaporization, which is 2259 J g^(-1). The temperature remains constant at 100°C during this phase change.
- Finally, draw a straight line with a positive slope from 100°C to 135°C to represent the heating process from steam at 100°C to steam at 135°C. The slope of this line represents the specific heat capacity of steam (2.02 J g^(-1) K^(-1)).
ii. Calculation of the energy needed to change the ice to steam:
To calculate the energy needed, we need to consider the different stages of the phase change and apply the relevant formulas.
- First, calculate the energy required to heat the ice from -20°C to 0°C using the formula:
Energy = mass × specific heat capacity × temperature change
Energy = 50 g × 2.06 J g^(-1) K^(-1) × (0°C - (-20°C))
- Next, calculate the energy required for the phase change from ice to water using the formula:
Energy = mass × heat of fusion
Energy = 50 g × 334.16 J g^(-1)
- Then, calculate the energy required to heat the water from 0°C to 100°C using the formula:
Energy = mass × specific heat capacity × temperature change
Energy = 50 g × 4.184 J g^(-1) K^(-1) × (100°C - 0°C)
- After that, calculate the energy required for the phase change from water to steam using the formula:
Energy = mass × heat of vaporization
Energy = 50 g × 2259 J g^(-1)
- Finally, calculate the energy required to heat the steam from 100°C to 135°C using the formula:
Energy = mass × specific heat capacity × temperature change
Energy = 50 g × 2.02 J g^(-1) K^(-1) × (135°C - 100°C)
To find the total energy needed, sum up all the individual energy values calculated above.