Term
How many significant figures in:
4057 |
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Definition
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Term
How many sig figs in:
0.57 |
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Definition
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Term
How many sig figs in:
1020 |
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Definition
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Term
How many sig figs in:
1020. |
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Definition
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Term
How many sig figs in:
50007 |
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Definition
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Term
How many sig figs in:
40.20 |
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Definition
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Term
How many sig figs in:
0.7500 |
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Definition
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Term
How many sig figs in:
0.00391 |
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Definition
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Term
How many sig figs in:
1020.0 |
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Definition
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Term
How many sig figs in:
0.056340 |
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Definition
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Term
| If too much solid unknown was put on a weighing paper on the balance, what should you do, and where do you put any extra solid? |
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Definition
| If you put too much on a weighing paper on the balance you should properly discard of the entire sample, for it cannot be returned to its original container and is now considered waste. |
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Term
| If too much solution was taken, what do you do with the excess solution? |
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Definition
| Properly discard of the execs solution in either designated waste deposit or in sink (if directed by lab). |
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Term
| What does tare mean, when do you tare something, and how do you do that? |
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Definition
| "Taring" is setting a balance to read zero by pressing the REZERO switch, with the empty container or weigher paper on the pan. The sample is then added to give a direct reading of the mass of the sample. This is used to determine the mass of a sample that requires a container or weighing square, but can only be used when the balance zero is not altered after taring until the final weighing is completed. |
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Term
| What do you do with your buret when done with the experiment? |
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Definition
| Rinse it thoroughly with DI water and then completely fill it with DI water, draining the water through the stopcock. When rinsed, flip the buret, place it back in the buret clamp, and open the stopcock. |
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Term
| How do you know how many sig figs to include in your answer when reading a measurement from equipment (such as a thermometer or pressure gauge)? |
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Definition
| You always record your answer with sig figs that extend one place value further than the piece of equipment is marked by. For example, if its marked in 1 degree increments then its estimated to 10 degree; if its marked in the 10th then it's measured to the 100th. |
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Term
| List two sources of error that would make percent recovery less than 100%. (Experiment 2: The Copper Cycle) |
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Definition
1. If some copper was lost in process of altering the copper's state, such as copper sticking to the beaker or filter paper.
2. if not enough HCl was added to dissolve all of the Copper. |
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Term
| Write an equation from this experiment that is a double displacement reaction. (Experiment 2: The Copper Cycle) |
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Definition
| Cu(NO3)2 (aq) + 2NaOH (aq) --> Cu(OH)2 (s) + 2NaNO3 (aq) |
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Term
| Write an equation from this experiment that is a single displacement reaction and an oxidation-reduction reaction. (Experiment 2: The Copper Cycle) |
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Definition
| CuO + HCl --> CuCl2 + H2O |
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Term
| Write an equation from this experiment that is a decomposition reaction. (Experiment 2: The Copper Cycle) |
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Definition
| Cu(OH)2 (s) --> CuO (s) + H2O (l) |
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Term
| In this experiment, copper (II) oxide is reacted with hydrochloric acid. Sulfuric acid can be used instead of hydrochloric acid. Write the balanced chemical equation, including states, for this reaction. (Experiment 2: The Copper Cycle) |
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Definition
| CuO (s) + H2SO4 (aq) --> CuSO4 (aq) + H2O (l) |
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Term
| In this experiment, copper chloride is reduced by zinc. Referring to the activity series of metals (Appendix 8), give another metal that would also reduce the copper chloride to copper. Write the balanced chemical equation, including states, for this reaction. (Experiment 2: The Copper Cycle) |
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Definition
| 3CuCl2 (aq) + 2Al (s) --> 2ACl3 (aq) + 3Cu (s) |
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Term
| In this experiment, the excess zinc is oxidized and made aqueous with the addition of hydrochloric acid. Other strong acids, such as cold sulfuric acid, may be used in this step, but warm nitric acid cannot be used. Why and what impact would this have on the percent recovery if warm nitric acid was used? (Experiment 2: The Copper Cycle) |
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Definition
| Warm Nitric acid cannot be used because it would dissolve copper as well. Percent recovery would drop significantly because not all of the zinc would oxidize. |
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Term
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Definition
| %recovery= (amount recovered/initial amount) x 100 |
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Term
| Why is it important to ignite the exit hydrogen and keep it burning? (Experiment 3: The Empirical Formula of an oxide) |
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Definition
| In order for oxide to be fully reduced and the reaction to be completed--indicated by the oxide's color change, it is necessary to ignite the exit hydrogen and keep it burning. |
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Term
| Why is it important to sweep hydrogen over the metal after it is reduced and is cooling? (Experiment 3: The Empirical Formula of an Oxide) |
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Definition
| So that the contents in the boat remain the metal alone rather than reacting to become an oxide again("re-oxidizing"). (Because going to measure mass of a metal once cooled.) |
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Term
| If the metal was not fully reduced, would the metal to oxygen ratio appear to be increased or decreased? Support your answer. (Experiment 3: The Empirical Formula of an Oxide) |
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Definition
| The ratio of metal to oxygen would appear to be increased because if the metal was not fully reduced, there would still be oxygen in the boat when weighing for metal. Consequently, it would appear that the mass of metal was greater and the mass of oxygen was less than it really is. |
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Term
| Using the periodic table, write another balanced equation showing how hydrogen could be generated using sulfuric acid with another metal. (Experiment 3: The Empirical Formula of an Oxide) |
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Definition
Copper (II)
Cu (s) + H2SO4 (aq) --> H2 (g) + CuSO4 (aq) |
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Term
| What physical parameter confirms the reaction is complete? (Experiment 4: Limiting Reagents) |
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Definition
| When the bubbling has subsided and the copper settles. |
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Term
| What physical evidence gives a clue as to which reactant is the limiting reagent? (Experiment 4: Limiting Reagents) |
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Definition
| Whichever reactant is all used up is the limiting reagent. Whichever reactant is still present in the solution (i.e. if you can see one physically), it is the excess. This would hint that the other reactant is the limiting reagent. physical evidence--> so...when the blue color is gone. |
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Term
| Why is the HCl added to the solution? (Experiment 4: Limiting Reagents) |
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Definition
| It dissolves the Aluminum so that it is in an aqueous state. The HCl enables the reaction to begin. |
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Term
| Why are the exact amounts of water and HCl relatively unimportant? (Experiment 4: |
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