A chemistry class is experimenting with iodine to see which common white powder items will react and make the iodine change color. Which item listed will have a chemical reaction with iodine?(1 point)
Responses
salt
powdered sugar
cornstarch
baking soda
When performing a scientific investigation on an unknown substance, how can an indicator help you determine if the substance is a starch?(1 point)
Responses
The indicator will change the taste of the substance.
The indicator will change the state of the substance.
The indicator will change the color of the substance.
The indicator will change the smell of the substance.
A student has an unknown powder and wants to determine what it is. Based on appearance, the student believes it is baking soda. When performing the vinegar test, what can the student expect to happen if it is baking soda?(1 point)
Responses
it will turn a blue-black color
it will crystallize into a sugar-like substance
it will bubble and foam
it will turn into a solid glass-like substance
A student is performing a Benedict’s test on an unknown substance. The student adds the reagent (the chemical required to make a color change), and nothing happens. Which conclusion can the student make?(1 point)
Responses
The test was inconclusive because the student forgot to add heat.
The test was inconclusive because the student needed to also test with iodine or vinegar.
The substance is not glucose based.
The substance is glucose based.
The item that will have a chemical reaction with iodine is baking soda.
An indicator can help determine if a substance is a starch by changing the color of the substance.
If the unknown powder is baking soda, it can be expected to bubble and foam during the vinegar test.
If the Benedict's test on an unknown substance does not produce any color change, the student can conclude that the substance is not glucose based.
just tell me which is correct
The correct responses are:
1. Baking soda will have a chemical reaction with iodine.
2. The indicator will change the color of the substance if it is a starch.
3. If the unknown powder is baking soda, it will bubble and foam during the vinegar test.
4. If the Benedict's test on an unknown substance does not produce any color change, the student can conclude that the substance is not glucose based.
i got a 50 WHY
I apologize if there was any confusion in my previous responses. Let's review the correct answers:
1. The item that will have a chemical reaction with iodine is baking soda.
2. An indicator will change the color of the substance if it is a starch.
3. If the unknown powder is baking soda, it will bubble and foam during the vinegar test.
4. If the Benedict's test on an unknown substance does not produce any color change, the student can conclude that the substance is not glucose based.
Please let me know if there are any further questions or if I can assist you with anything else.
The item that will have a chemical reaction with iodine is baking soda.
When performing a scientific investigation on an unknown substance, an indicator can help determine if the substance is a starch by changing the color of the substance.
If the student's unknown powder is baking soda, when performing the vinegar test, the student can expect it to bubble and foam.
If the student is performing a Benedict's test on an unknown substance and nothing happens after adding the reagent, the conclusion the student can make is that the substance is not glucose based.
To determine which common white powder item will react with iodine, the chemistry class can perform a simple experiment. They can place a small amount of each item in separate test tubes or containers, then add a few drops of iodine solution to each one. The class should observe if the iodine changes color when it comes into contact with each item. The item that causes a color change indicates a chemical reaction with iodine.
To determine if a substance is a starch using an indicator, the class can use an iodine indicator. This can be made by mixing iodine with water or alcohol. When the iodine indicator is added to the substance being tested, it will change color if the substance is a starch. The indicator will turn from its original color (usually brown) to a dark blue or black color in the presence of starch.
If a student believes they have baking soda and they want to confirm it using the vinegar test, they can mix a small amount of the unknown powder with vinegar. If it is indeed baking soda, a chemical reaction will occur, resulting in bubbling and foaming due to the release of carbon dioxide gas. This is a characteristic reaction of baking soda when it reacts with an acid like vinegar.
If a student performs a Benedict's test on an unknown substance and nothing happens after adding the Benedict's reagent, it can be concluded that the substance is not glucose-based. Benedict's reagent is specifically used to test for the presence of reducing sugars, including glucose. If there is no color change or formation of a precipitate, it means the substance does not contain glucose or is not a reducing sugar.
Remember that these explanations provide general guidelines and should not replace actual laboratory procedures or professional guidance.