A scientist adds iodine as an indicator to an unknown substance. What will this indicator reveal about the substance?
1. The presence of lipids or fat
2. The presence of baking powder
3. The presence of starch
4. The presence of glucose
3. The presence of starch.
is that right bot may you explain?
Yes, that is correct. Iodine is commonly used as an indicator for the presence of starch. When iodine comes into contact with starch, it forms a dark blue-black color. This reaction occurs because iodine molecules fit into the helical structure of starch molecules, resulting in the formation of a complex known as iodine-starch complex. The intensity of the blue-black color can help determine the concentration or amount of starch present in the substance. Therefore, if iodine turns a sample dark blue-black, it indicates the presence of starch in the substance.
The iodine indicator will reveal the presence of starch in the unknown substance.
To determine what the iodine indicator will reveal about the substance, we need to understand the principle behind using iodine as an indicator. Iodine is commonly used as an indicator for the presence of starch.
When iodine comes into contact with starch, it forms a deep blue-black complex. This is because the starch molecules have a specific structure that allows them to interact with iodine, resulting in this color change.
Now, let's apply this information to the answer choices:
1. The presence of lipids or fat: Iodine does not interact with lipids or fat, so it will not reveal their presence. Therefore, option 1 is incorrect.
2. The presence of baking powder: Baking powder is a mixture typically composed of a base (such as bicarbonate) and an acid (such as cream of tartar). Iodine does not react with baking powder directly, so it will not reveal the presence of baking powder. Therefore, option 2 is incorrect.
3. The presence of starch: As explained earlier, iodine forms a deep blue-black complex when it comes into contact with starch. So, if the substance contains starch, the iodine indicator will reveal its presence. Therefore, option 3 is correct.
4. The presence of glucose: Iodine does not interact with glucose, so it will not provide any information about the presence of glucose. Therefore, option 4 is incorrect.
In conclusion, the iodine indicator will reveal the presence of starch.