All categories

3 years ago

6. Alex wanted to find out what toothpaste made teeth the cleanest. Everyday she brushed her

Chemistry

1 answer:

vichka [17]3 years ago

3 0

Answer:

a) Independent variable (IV): toothpase brand

b) Dependent variable (DV): amount of plaque left

c) Control: water

d) Constants: amount of toothpaste, kind of toothbrush, how long the toothbrushing took.

Explanation:

In an experiment there usually be independent variable, dependent variable, control gropus, and constants.

The independendent variable is the variable whose impacts on other varbiale. Then, the independent variable is manipulated or changed by the scientist (the person that designs or perform the experiment).

In this case, Alex is changing the brand of toothpaste: Crest, Colgate, and Close-Up. So the answer to the first question is brand of toothpaste:

a. Independent variable (IV): toothpaste brand.

The dependent variable is the variable that changes by the effect of changing the independent variable. It is the variable whose behavior you want to explain in terms of the independent variable.

In this case, Alex wants to determine the effect of the toothtpaste brand on the plaque, so the dependent variable is how much plaque is left.

b. Dependent variable (DV): how much plaque is left.

The control is a group of experiments used for comparison. This is, you do not include the independent variable in them. In this example it is the set of experiments made with only water. The scientist will be able to compare the results of using toothpase with no using toothpaste on the plaque when he includes a group of experiments where no toothpaste is used but water.

c. Control: water

In order to state if it is the change in the independent variable what causes or explains the results on the dependent variable, the scientist must make sure that no other changes occur during the experimentation.

In this case, it is not stated which other conditions Alex made sure to remain constant, but for sure they should include the amount of toothpaste used, the kind of teethbrush, and the time of brushing.

d. Constants: presumably, the amount of toothpase, the kind of toothbrush, and the time of brushing.

You might be interested in

Calculate the mass of 4.50 moles of Ca3(PO3)4

Ivahew [28]

Stoichiometry:
First, calculate the number of grams for one mole of Ca3 (PO3)4
(3 * (Mass of Ca)) + (4 * (Mass of P + (3 * Mass of Oxygen)))
= (3*40.08) + 4(30.97 + (3*16.00))
=(120.24) + 4(78.97)
=436.12 g / mol Ca3(PO3)4
This means there are 436.12 g per 1 mole of Ca(PO3)4. Since there are 4.50 moles of Calcium Phosphate, mulitply the molar mass of Ca(PO3)4 by 4.50 and you should get 1962.54 g. Since there are 3 sigfigs, the final answer is 1960 g.

on a side note: I put in all my work in case 1. your periodic table if different, 2. my work is wrong, 3. you put in the question wrong because I feel that the actual compound would be Ca3(PO4)3 instead of Ca3(PO3)4 (if this is the case, the answer should be 1820 g).

8 0

4 years ago

Read 2 more answers

Classify each of the following as elements (E), compounds (C) or Mixtures (M). Write the letter X if it is none of these. ______

Lana71 [14]

Answer:

Diamond - E

Sugar- C

Milk - M

Iron- E

Air- M

Sulfuric Acid- C

Gasoline - M

Electricity- X

Krypton- E

Bismuth - E

Uranium - E

Kool-Aid -M

Water - C

Alcohol - C

Pail of Garbage - M

Ammonia - C

Salt - C

Energy - X

Gold - E

Wood - M

Bronze - M

Ink - M

Pizza - M

Dry Ice - C

Baking Soda - C

Explanation:

An element is the smallest part of a substance that is capable of independent existence. An element cannot be broken down into any other substance. Krypton, Bismuth etc are all elements.

A compound is a combination of two or more elements which are chemically combined together e.g NH3, CO2 etc.

A mixture is any combination of substances that are not chemically combined together. E.g Pizza, milk etc

5 0

3 years ago

Which sample of copper has atoms with the lowest average kinetic energy? 1. 10. g at 45°C 2. 20. g at 35°C 3. 30. g at 25°C 4. 4

blagie [28]

I would say 4. 40. g at 15°C because kinetic energy is related to temperature and not mass, so the lower temp would give you lower KE

7 0

3 years ago

Read 2 more answers

How does rhenium apply to real life

riadik2000 [5.3K]

Answer: Rhenium is used as an additive to tungsten- and molybdenum-based alloys to give useful properties. These alloys are used for oven filaments and x-ray machines. It is also used as an electrical contact material as it resists wear and withstands arc corrosion.

Explanation:

4 0

3 years ago

Violet light has a wavelength of 6. 80E-7 m. What is the frequency?

Sever21 [200]

Answer:

violet has a frequency of 668-789 THz :)

Explanation:

5 0

2 years ago