A big waste of time around the balances is to try to measure

A big waste of time around the balances is to try to measure out 0.500 g of benzoic acid exactly when what is most important in science is to tell the truth and know how much benzoic acid you actually put in your procedure or reaction, whether it was 0.495 g or 0.512 g for example. In fact, a simple indicator of fraud in science is when all the numbers are perfect.

Select one:

True

False

Question 2

Not yet answered

Marked out of 4.00

Flag question

Question text

Match a picture on the left to its name on the right.

Question 3

Not yet answered

Marked out of 4.00

Flag question

Question text

Match a use on the left to the best type of clamp you should use on the right.

For holding a test tube

For holding up a funnel

For holding a hot Erlenmeyer flask

For clamping down a filter flask

Question 4

Not yet answered

Marked out of 1.00

Flag question

Question text

True or False, benzoic acid melts in water?

Select one:

True

False

Question 5

Not yet answered

Marked out of 8.00

Flag question

Question text

Match a purpose on the left to a procedure that you carried out in recrystallizing benzoic acid.

To isolate benzoic acid from water

To dry the crystals more quickly

To remove insoluble impurities

To determine the purity of benzoic acid

To hasten filtration

To dissolve benzoic acid

To induce crystallization

To avoid premature crystallization

Question 6

Not yet answered

Marked out of 1.00

Flag question

Question text

If you measured out 0.537 g of impure benzoic acid but recovered only 0.226 g after recrystallization, what is your percent recovery? Round to a whole number answer without any decimal point or units.

Answer:

Question 7

Not yet answered

Marked out of 1.00

Flag question

Question text

Which is not a reason why the percent recovery or yield of a compound is higher than 100 %?

Select one:

a. The compound isolated is impure.

b. Your calculations to determine percent recovery or yield are incorrect, for example you used the reciprocal of the correct ration.

c. The compound isolated is still wet.

d. Your measurements of the weight before and after the procedure or reaction are incorrect.

e. Matter was created.

Question 8

Not yet answered

Marked out of 1.00

Flag question

Question text

A graph of temperature (°C) versus solubility of benzoic acid in water (g/L) has a good exponential fit, y = 1.479e^0.0357x, indicated by the Goodness of Fit R² = 0.9955. Given that you used 12.6 ml of water to dissolve 0.616 g of benzoic acid, what was the actual temperature of your recrystallization setup according to this exponential equation? Don\'t forget that there are 1000 ml in a liter. Round to a whole number answer without any decimal point.

Answer:

Question 9

Not yet answered

Marked out of 1.00

Flag question

Question text

You may have been told to measure the melting point of your benzoic acid after crystallization. What is the expected result compared to the benzoic acid that you were given?

Select one:

a. A higher sharper melting point because we are 0.7 miles above sea level.

b. A lower, less-sharp melting point because the benzoic acid is still wet.

c. About the same melting point because the original sample was already pure.

d. A lower, less-sharp melting point because we are 0.7 miles above sea level.

e. A higher sharper melting point because the benzoic acid is now more pure.

	Answer 1Choose...Test Tube ClampRing ClampUniversal ClampBurette Clamp
	Answer 2Choose...Test Tube ClampRing ClampUniversal ClampBurette Clamp
	Answer 3Choose...Test Tube ClampRing ClampUniversal ClampBurette Clamp
	Answer 4Choose...Test Tube ClampRing ClampUniversal ClampBurette Clamp

Solution

4) False, Benzoic acid does not melt in water.

6) Percent recovery = (0.226/0.537)*100 = 43%

7) Answer- e) Matter was created.

8) Answer- e) A higher sharper melting point because the benzoic acid is now more pure.