Mg turnings are dropped into a coffee cup calorimeter containing a solution of 2
ID: 984547 • Letter: M
Question
Mg turnings are dropped into a coffee cup calorimeter containing a solution of 25.0 mL of 3.0M HCl(aq) and 35.0 mL of water. (Mg is the limiting reagent). The temperature of the reaction was measured for about 500 seconds. The temperature curve is shown below. The slope and intercept can be calculated using the slope and intercept using the linear part of the graph after the reaction is complete. The graph can also be used to determine the starting time of the reaction.
45 40 35 30 25 20 15 50 115 200 250 5 40 4 00 First pick points for the linear part of the graph for your slope intercept analysis. · You may remember from math that slope intercept formula has the form: y = mx + b. The program will generate a trendine and the slope intercept formula for you after finding suitable points for the program. You need to pick a minimum point and a maximum point for the line that is in the linear region. . Picking a beginning point for the trend line too near the inflection point of the temperature curve will distort your slope and create an error in your final temperature. Picking a final point for the trend line not near enough the end of the curve will not survey enough data to get an accurate slope. . Pick a beginning x point in seconds for your slope analysis (no units). 10 Pick a final x point on the graph (in seconds) for your slope analysis (no units). 350 At what time (in seconds) is the start of the reaction? (no units in answer) 50 Submit Answer Incorrect. Tries 2/99 Previous TriesExplanation / Answer
The reason why this is incorrect is because you didn't follow the instructions of solving this. You need to pick points from the linear area. This area is after the 10 s. The linear area begins at 100 s and ends in 500 s. I will choose 150 s as a beggining point, and a final of 400 s.
the reaction begins at 50 s indeed.
Now from here you can calculate the slope which is:
m = y2-y1 / x2-x1
m = 34 - 37 / 400 - 150 = -0.012
Hope this helps