CHM130
Lab 3
Identification of Chemical Change
Name: Nolan Strommer
A. Data Table (24 points)
Place your completed data table here:
Reactants Predictions Before
Combining Observations After
Combinin g
Starch + I2 It becomes purple It becomes blue and a little purple.
Food coloring + NaOCl The color of the food coloring will disappear. The color of food coloring is on the top of NaOCI, NaOCI is under the food coloring.
Food coloring + CH3COOH The color will be the same as the food coloring The color becomes to the food coloring color.
Food coloring + NaOCl
+ CH3COOH It will have foam and the food coloring color. It has foam in the color of the food coloring.
Red cabbage + NH3 It becomes green It becomes green and a little yellow.
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MgSO4 + NH3 The result will be a sediment It has a little precipitate.
MgSO4 + Na2CO3 Nothing will happen It has a little white precipitate.
B. Follow-Up Questions
1. What type of macroscopic evidence for chemical change did you observe during this experiment? Give at least three different examples. (15 points)
Answer:
The first example of macroscopic change I observed is the color change from the combination of Starch + I2. The second example of macroscopic chemical change is the sediment formed by the combination of MgS04 and NH3. The third example is the foam from the mixture of Na2CO3+ CH3COOH
2. Which reactions, if any, do you believe showed no evidence of chemical change? Justify your reasoning. (15 points)
Answer:
The combination of NAHCO3 and NH3 is a reaction that does not show any changes from a chemical standpoint. This is due to the fact that both of these compounds are bases and therefore do not have a reaction.
3. When two solutions combine and a solid substance is formed, this solid is called a precipitate. In your experiments, if the clear reactant solutions you combined together formed a cloudy product, then a precipitate (solid substance) was formed. Describe the precipitates (according to color and clarity) and the substances that formed them. (18
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Therefore Iodine can be utilized to detect the presence of starch since the reaction of I2+ I- gives us I3 - . What this means is that any substance that becomes blue/black after iodine has been added to it proves that the substance has starch in it. Interestingly enough, when Iodine is added either to white rice or sweet potatoes, these two foods turn to the blue black color that confirms the presence of starch. However, If I add iodine to a banana, it only turns yellow which confirms that the banana does not contain iodine.
6. Red cabbage juice is a natural, universal indicator. When a solution of red cabbage is red to pink, it indicates that a solution is acidic. When it is green to yellow, it indicates that a solution is basic. When it is purple to blue, it indicates a solution is neutral. Would you characterize vinegar and ammonia as acids or bases? Explain. (15 points)
Answer:
Vinegar is acid because red cabbage juice+CH3COOH will become red and a little pink. Ammonia is base because NH3 which ammonia contains add red cabbage juice will become green and
The experiment is to observe a variety of chemical reactions and to identify patterns in
Vinegar is a common household product, when mixed with the indicator, phenolphthalein, it turns pink. This indicates that Vinegar is acidic.
The main objective of this experiment is to differentiate between a physical change and a chemical change.
(15 points) There was one combination that did not have any reaction when tested. This combination was the MgSO4 and CH3COOH. The reason that the reaction did not happen is because they created a mixture and not a chemical change. 3.
Purpose/Hypothesis: The purpose of this experiment is to use both cabbage juice and pH paper to determine the pH of household items. This way, we can tell which products are basic and which one are acidic. If we use cabbage juice as an universal pH indicator by comparing it to pH paper then pH determined by the cabbage juice will be unstable because by using cabbage juice, it can be different depending on how diluted it is.
The Vitamin C turned to a red/orange color with no physical/chemical reaction. For the salt the solution turned to an orange color with no physical/chemical reaction. With the Alka-Seltzer, the solution turned to a brown color with no reaction as well. Last but not least, the Baking soda turned to an orange/brown color with no reaction.
A chemical reaction is when substances (reactants) change into other substances (products). The five general types of chemical reactions are synthesis (also known as direct combination), decomposition, single replacement (also known as single displacement), double replacement (also known as double displacement), and combustion. In this lab, the five general types of chemical reactions were conducted and observations were taken before, during, and after the reaction. Then the reactants and observations were used to determine the products to form a balanced chemical equation. The purpose of this lab was to learn and answer the question: How can observations be used to determine the identity of substances produced in a chemical reaction?
The nichrome wire exposed to the acid there was nothing that occurred. Therefore, it was neither a chemical nor physical change.
The objective of this experiment will be to combine various substances, liquids and metals, and to observe their behavior when they are combined. The types of reactions observed shall determine the nature of these reactions: physical or chemical.
There was an assortment of different changes indicating that chemical changes were taking place such as change in color or chemicals bubbling when combined with another chemical.
C.|NH3 + BTB|A4|The mixture is a lighter royal blue under white paper and a darker royal blue under black paper. The mustard yellow would be an acidic indicator and the royal blue a basic indicator. |
Purpose: The purpose of this experiment is to observe a variety of chemical reactions and to identify patterns in the conversion of reactants into products.
Table 2: Consists of color extract taken from a red cabbage for a natural indicator. The pH reading that was measured by using the pH meter and the result of the pH reading to determine whether the solution was acidic or basic.
For example, silver nitrate formed a white precipitate when it was tested with ammonium chloride. In contrast, unknown 3 did not formed any precipitate with ammonium chloride. Ammonium chloride change the color of unknown 3 to a light green while the solution of silver nitrate and ammonium chloride was cloudy white solution. Likewise, the metal in unknown 3 could have been Calcium neither. Data and observation shows that calcium nitrate whether formed a white precipitate or did not react at all while unknown 3 formed an orange precipitate. Therefore, silver and calcium are not the two metal present in unknown
By using acid-base titration, we determined the suitability of phenolphthalein and methyl red as acid base indicators. We found that the equivalence point of the titration of hydrochloric acid with sodium hydroxide was not within the ph range of phenolphthalein's color range. The titration of acetic acid with sodium hydroxide resulted in an equivalence point out of the range of methyl red. And the titration of ammonia with hydrochloric acid had an equivalence point that was also out of the range of phenolphthalein.. The methyl red indicator and the phenolphthalein indicator were unsuitable because their pH ranges for their color changes did not cover the equivalence points of the trials in which they were used. However, the