Technical Problem Solving
Huntley Invite
February 22, 2014
TEAM NAME ________________________________
TEAM NUMBER___________________________
PARTICIPANT’S NAME________________________
Labs –
Newton’s Law of Cooling
Determination mass plated
Lab 1 Newton’s Law of Cooling
Show a complete lab write-up to determine the temperature of the oven the beakers of water were in.
Materials:
Drying oven
Beaker
Procedure: [5]
1. Take the temperature of the room.
2. Take the temperature of the water every 30 seconds
3. Or every minute or some logical time
4.
5.
6.
7.
8.
9.
10.
Water
Thermometer
Data: Create a proper data table including all necessary data with the titles and units on the top row and numbers below. [7]
Temp (⁰C)
Time (sec)sec
Graph:
Draw a complete, appropriate graph of the data collected showing the effect of time on temperature. [10]
Calculations/Analysis: -- SHOW ALL work and circle or box your final answer with units and sig figs.
1. What is the equation for Newton’s Law of Cooling? [2]
2. Solve for k and show all work. [5]
3.
What temperature was the oven where the water was retrieved? (water was removed at the beginning of the event) [5]
4.
If the temperature of the water is more similar to the temperature of the room, is the rate of change faster or slower?
Explain using the graph.[2]
It is slower. The difference in temp impacts the slope
5. Define ambient temperature. [2]
6. Another group solved for k and they found k to be 8% less than your value. Do you think they started recording
data before you, after you, or cannot be determined. Explain. [2]
7. Another group split their water into two samples and determined k twice for a smaller quantity of water.
a. Will their water cool faster or slower than yours. [1]
b. Will their k be larger or smaller than yours. Explain. [3]
8.
If your water sample was kept in a thermos when it left the oven, what variables would change? [3]
9.
If your beaker of water was put in an ice water bath instead of the room, how would your graph change at the
end? [1]
10. Would the following changes increase or decrease the temperature of the water after two hours? [3]
a. A fan was set to blow over the water.
b. The water was stirred.
c. The water was spread out.
Lab 2 Determine Mass plated
Use the picture below and the data table for this lab activity.
Purpose: To determine the mass plated in an electrolytic cell.
Materials:
1. This is an electrolytic cell. What solution should be used? [2]
a. AgNO3
b. Zn(NO3)2
c. NaNO3
d. NaCl
Write the Procedure required to determine the amperage and acquire the data table below [5]
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Mass both metal strips
Connect wires
Insert into solution
Time for 5 minutes
Mass both metal strips
Data:
Initial Mass of
silver (g)
10.000
Final Mass of
silver (g)
Predict (#3)
Initial
Mass of
Zinc (g)
10.000
Final Mass
of Zinc (g)
Predict (#4)
Current
(amp)
0.5000
Voltage
of
Battery
(V)
2.00
Time
elapsed
(minutes)
5.000
Concluding Questions: Show work and box in answers. Illegibility in work and answers will be penalized.
1. To the correct number of significant figures, what was the total loss of mass of solid metal? Show work.[3]
20.000-9.832-10.051=
2. Show work to calculate the time required in seconds for the plating to occur. [3]
3. Show work to calculate the change in mass of silver (include a + or – sign)? [3] (9.832g)
4. Show work to calculate the change in mass of Zinc (include a + or – sign)? [3] (10.051g)
5. Write the oxidation reaction that occurred including states of matter. [3]
Ag Ag+ +1e
6. Write the reduction reaction that occurred including states of matter. [3]
Zn+2 +2e-  Zn
7. Which metal represents the anode? Explain. [2]
Ag
8. Is the chemical reaction that occurred galvanic? Explain. [2]
No, battery required. Ecell is negative
9.
What is the value of Ecell assuming standard conditions? Show work. [3]
0.04V
10. What minimum voltage is required for the electrolytic reaction that occurred to take place? [2]
0.05V
11. How many moles of Zinc form? [3]
12. What was the current of the system? [1]
0.50 amp
13. What effect (Increase, decrease, or no effect) in final mass of the zinc plated 5 minutes if the following
occurred? [6]
a. Voltage was halved.
decrease
b. Mass of the silver was doubled.
No effect
2+
c. Concentration of Zn increased.
increase
d. Ni+2 ions were added.
decrease
+2
e. Mg ions were added.
No effect
f. Increase the mass of solid zinc.
No effect