Hi! Can you please check if my answers are correct? And, can you please tell me any other details you think are important to add. Also, the last two questions i have no clue how to answer. can you help? thanks so much!
3.A burning candle produces a luminous flame. What is the fuel for the burning candle? Why is the flame luminous?
- The fuel for the burning candle is oxygen. With an insufficient supply of oxygen, small carbon particles are produced, which, when heated to incandescence, produce a yellow, luminous flame. The combustion products may, in addition to carbon dioxide and water, include carbon monoxide.
4. Part C. 1c. The solid is not completely submerged in the water. Will this technique error increase, decrease, or have no effect on the reported density of the solid? Explain.
- If the solid is not completely submerged in the water, the reported density would increase. The volume would be less than it is supposed to be, and so the density would be greater than the correct reading.
5. Part C.2. Suppose that after delivery several drops of the water cling to the inner wall of the pipet (because the pipet wall is dirty). Will this technique error increase, decrease, or have no effect on the reported density of water? Explain.
- If several drops of water cling to the inner wall of the pipet, the volume of the water would be a lower value then what the pipet was calibrated to. So, the density of the water would be increased. The mass that you are weighting will be greater than it should be, which gives you a greater density.
6.Part C.3. The unknown liquid is volatile. If some of the liquid evaporates between the time the liquid is delivered to the beaker and the time its mass is measured, will the reported density of the liquid be too high, too low, or unaffected? Explain.
- The formula for density is: mass/volume. Volume is not affected since the beaker is not expanding nor shrinking. Since some of the liquid evaporated between the time the liquid was delivered to the beaker to the time the mass was measured, the mass measures are less. As a result, the reported density of the liquid would have an outcome lower than expected.
1. Part A.1. If you have a properly adjusted hot flame, which is pale blue with three distinct cones, what is observed if the gas control valve is slightly closed? Explain.
2. Part A.1. If you have a properly adjusted hot flame, which is pale blue with three distinct cones, what is observed if the air-control valve is slightly closed? Explain.
1 answer
4 is ok.
5. I can't be sure what you did but from your answer I have assumed you measured a liquid with a pipet, dispensed into a container, WEIGHED the liquid from the pipet and calculated the density from that. If that is right, then I don't agree with the answer. As far as your experiment is concerned, you dispensed the volume OF THE PIPET (even though not all of came out of the pipet). Then you weighed the liquid dispensed and that weighs less since less is present. d = m/v; mass is less, volume is the labeled volume of the pipet so density is less.
6 is ok.
For the two questions at the end, I suggest you do this in the lab and you will know the answer.