Questions posted in Chemistry

Which type of change must occur to form a compound? (1) chemical (3) nuclear(2) physical (4) phase?

Let's go through each of the answers and think about why they work or don't work. 

Chemical forms compounds. 

Nuclear changes the element completely. We're going to use the sun as an example. The sun is in a state of plasma. It's really hot and has all these particles hitting into each other. The nucleus' of atoms are hitting into each other forming larger elements. It's real crazy. Nuclear is not correct. 

Physical cannot form a compound. 

ANSWERED AT 06/12/2019 - 04:38 PM


QUESTION POSTED AT 06/12/2019 - 04:38 PM

What is the volume of 220g of an object with a density of 55g/cm^3

Volume = mass / density

220.0g is our mass
55.0g/cm^3 is our density

(220g) / (55g/cm^3) = 4cm^3

ANSWERED AT 06/12/2019 - 04:32 PM


QUESTION POSTED AT 06/12/2019 - 04:32 PM

Which changes of state result in a decrease in the kinetic energy of the particles?

Liquid into solid, gas into a liquid, gas into a solid (deposition).
Kinetic energy is all about motion. If you think about it, the particles are going from a more chaotic state to a more orderly arrangement which reduces the kinetic energy. 


ANSWERED AT 06/12/2019 - 04:31 PM


QUESTION POSTED AT 06/12/2019 - 04:31 PM

Which atomic model states that it is impossible to know the exact location of electrons around the nucleus?

The correct answer is electron-cloud model. This model states that electrons don't go around in an eliptical way but rather completely erratically and uncontrolably and this is why it can't be known where they are or how they will behave. They form sort of like a cloud of many electrons that move erratically so you have to check it to see where it is.

ANSWERED AT 06/12/2019 - 04:29 PM


QUESTION POSTED AT 06/12/2019 - 04:29 PM

What do all four of these molecules have in common? A. They are essential to life. B. They carry signals. C. They are water soluble. D. They act as a source of energy

I did a quick search and found the diagram. Let's go through these and solve by elimination. 

B. Proteins can act as receptors which I guess could be considered a signal, but the rest of the molecules do not. B is incorrect. 

C. Lipids are not water soluble. An example of lipids are fats, and oils. Have you ever tried combining water and oil? Think about salad dressing, it does not mix. C is incorrect.

D. Carbohydrates and lipids are sources of energy, but nucleic acids and proteins are not. D is incorrect. 

The answer is A. because we know that our bodies are made up of nucleic acids, protein, fats, and we need carbohydrates in order to live normal, healthy lives. 

ANSWERED AT 06/12/2019 - 04:28 PM


QUESTION POSTED AT 06/12/2019 - 04:28 PM

A 4,000 mL solution of AgNO3 contains 17.00 g of solute in water. Calculate the molar concentration of the solution.

The molarity is moles/liters.

First, convert 4,000 mL to L:

4000 mL --> 4 L

Now, you must convert the 17 g of solute to moles by dividing the number of grams by the molar mass. The molar mass of AgNO3 is 169.87 g/mol:

17 / 169.87 = .1

Now that you have both the number of moles and the liters, plug them into the initial equation of moles/liters:

.1/4 = .025

ANSWERED AT 06/12/2019 - 04:27 PM


QUESTION POSTED AT 06/12/2019 - 04:27 PM

Why did the identity of the water not change when it formed ice? assroo.

It didn't change because nothing but the temperature to make it freeze went into it so it is still the same substance. Hope this helped!

ANSWERED AT 06/12/2019 - 04:25 PM


QUESTION POSTED AT 06/12/2019 - 04:25 PM

What do the formulas for table salt, NaCl, and water, H2O indicate about the compounds?

The formulas indicate the number of elements in each compound. Notice the difference in ratios: 
NaCl is 1:1, while H2O is 2:1.

ANSWERED AT 06/12/2019 - 04:21 PM


QUESTION POSTED AT 06/12/2019 - 04:21 PM

The ratio of hydrogen atoms to sulfur atoms in sulfuric acid, H2SO4 is

The question is asking the ratio of H to S in H2SO4.
In the following molecular formula, there are 2 hydrogen and 1 sulfur
This means that the ratio is 2:1.

ANSWERED AT 06/12/2019 - 04:21 PM


QUESTION POSTED AT 06/12/2019 - 04:21 PM

What is the mass of 2.50 ×1022 molecules of NaOH (Molar mass = 40.0 g/mol)?

Two things are given to us: The "molar mass" of NaOH and the number of molecules of NaOH

The molar mass is different from "mass"; 1 mole of NaOH is equal to 40.0g/mol.
When the question asks, what is the mass? It is referring to how many grams there are. 

First, we are going to convert the molecules to atoms using Avogadro's number (=6.02 x 10^23)

(2.50 x 10^22 molecules) x (6.02 x 10^23 atoms) = 0.042 mol

Next, we are going to convert from moles to grams.

 0.042 mol of NaOH x 40.0 g of NaOH/1 mole = 1.68g of NaOH.

There are 1.68 grams in 2.50 x 10^22 molecules of NaOH.



ANSWERED AT 06/12/2019 - 04:20 PM


QUESTION POSTED AT 06/12/2019 - 04:20 PM

What keeps the cell together and controls what goes into and out of the cell?

The membrane keeps the cell together and controls what goes in and out of the cell.

ANSWERED AT 06/12/2019 - 04:19 PM


QUESTION POSTED AT 06/12/2019 - 04:19 PM

The defining characteristic of deserts is their high daytime temperatures. true or false ?

This is a weird question. 

Deserts do have very high day time temperatures, but they also have extremely low temperatures at night because of a lack of water. If you live in a city surrounded by water, you'll find that it will actually be warmer in the city at night than it would in a town further in-land. 

ANSWERED AT 06/12/2019 - 04:18 PM


QUESTION POSTED AT 06/12/2019 - 04:18 PM

What is the molarity of a 10 L solution containing 5.0 moles of solute?

Explanation:

Number of moles consisting in a liter of solution is known as molarity.

Mathematically,       Molarity = \frac{\text{no. of moles}}{\text{Volume in one liter}}[/tex]

It is given that volume is 10 liter and there is 5.0 moles of solute. Hence, we will calculate the molarity as follows.

                 Molarity = \frac{\text{no. of moles}}{\text{Volume in one liter}}

                                = \frac{5.0 mol}{10 liter}

                                = 0.5 mol/L

Thus, we can conclude that molarity of the given solution is 0.5 mol/L.

ANSWERED AT 06/12/2019 - 04:18 PM


QUESTION POSTED AT 06/12/2019 - 04:18 PM

What is the correct formula for calcium fluoride

The answer would be CaF2

ANSWERED AT 06/12/2019 - 04:17 PM


QUESTION POSTED AT 06/12/2019 - 04:17 PM

What properties you can observe or measure?

We can observe physical properties of elements and compounds without changing the substance.

Examples of physical properties: Density, color, boiling point, state of matter, appearance: dull or shiny, etc. 

But we can also observe and measure chemical properties by reacting a substance with something else. For example, like mixing baking soda and vinegar together. The vinegar reacts with the baking soda and produces carbon dioxide: a new substance. 

Some examples of chemical properties: Flammability, amount of heat that is released during combustion, toxicity (how much damage it causes to other organisms), radioactivity, and ability to oxidize (when you have metal that becomes rusty looking).

ANSWERED AT 06/12/2019 - 04:14 PM


QUESTION POSTED AT 06/12/2019 - 04:14 PM

What is the name of the movement of the Earth around the Sun as pointed out by letter J.


it is called the Earth's rotation

ANSWERED AT 06/12/2019 - 04:14 PM


QUESTION POSTED AT 06/12/2019 - 04:14 PM

What would most likely be included in the “Analysis” section of a lab report?

The purpose of the analysis section of a lab report is to detail what happened in the lab and what the outcome of the project was as a result of said events.

ANSWERED AT 06/12/2019 - 04:13 PM


QUESTION POSTED AT 06/12/2019 - 04:13 PM

Carefully looking at an object or process

observation

They utilize and make use of the scientific method in order to have clear basis and evidence for their investigations. Research method is always used to answer every scientific inquiry and in gaining evidential data or knowledge. The scientific method has the following process or at least undergoes the process of
1. Observation
 
2. Hypothesis 
3. Experimentation 
4. Interpretation of data 
5. Evaluating the data 
6. Passing and recording the data 

These steps are crucial and the empirical data that these scientists obtain are very important to keep that is why research paper, thesis and dissertations exists.

ANSWERED AT 06/12/2019 - 04:08 PM


QUESTION POSTED AT 06/12/2019 - 04:08 PM

What would happen if a decomposers were absent from the forest ecosystem?

There would be no way that the nutrients could go back into the ecosystem and there would be tons of dead animals lying around.

ANSWERED AT 06/12/2019 - 04:05 PM


QUESTION POSTED AT 06/12/2019 - 04:05 PM

What happens to the molecules in a gas when it condenses?

When gas molecules condence they become a liquid and if the liquid molecules condence they turn into a solid but the solid molecules cannot condence

ANSWERED AT 06/12/2019 - 04:03 PM


QUESTION POSTED AT 06/12/2019 - 04:03 PM

If you were asked to convert 25 kg to the unit mg, which of the following would be the first fraction used in the conversion?

Divide twenty-five by one thousand

ANSWERED AT 06/12/2019 - 04:00 PM


QUESTION POSTED AT 06/12/2019 - 04:00 PM

What element is added to toothpaste and city water systems to help tooth decay?

Answer is Fluorine.
Hope it helps and pls mark as the best answer. :-)

ANSWERED AT 06/12/2019 - 03:59 PM


QUESTION POSTED AT 06/12/2019 - 03:59 PM

The mass in a chemical reaction is found in

a chemical compound

ANSWERED AT 06/12/2019 - 03:58 PM


QUESTION POSTED AT 06/12/2019 - 03:58 PM

The mass in a chemical reaction is found in

The energy produced by the reaction

ANSWERED AT 06/12/2019 - 03:58 PM


QUESTION POSTED AT 06/12/2019 - 03:58 PM

What is the term of movement in a particular direction

Force its movement is force because of sent it in that direction

ANSWERED AT 06/12/2019 - 03:46 PM


QUESTION POSTED AT 06/12/2019 - 03:46 PM

What are the subatomic particles of barium

Electrons (negative charge, and orbits the nucleus), Protons (positive charge, and is in the nucleus) and Neutrons (no charge, and is in the nucleus)

ANSWERED AT 06/12/2019 - 03:43 PM


QUESTION POSTED AT 06/12/2019 - 03:43 PM

Which of the following belongs in rectangle A of the diagram

Wheres the diagram

We have to see the diagram to answer your question

ANSWERED AT 06/12/2019 - 03:33 PM


QUESTION POSTED AT 06/12/2019 - 03:33 PM

How does a graph with no trend differ from a graph with anomalous data points

Because you need it to see if your looking at the right thing

ANSWERED AT 06/12/2019 - 03:32 PM


QUESTION POSTED AT 06/12/2019 - 03:32 PM

Boron occurs naturally as two isotopes. What is the difference between these isotopes? a)They have different numbers of electrons and different charges. b)They have different numbers of neutrons and different charges. c)They have different numbers of protons and different mass numbers. d)They have different numbers of neutrons and different mass numbers.

Atoms are made of 3 types of subatomic particles that are electrons, protons and neutrons.
the number of protons in the atom is called the atomic number. the atomic number is characteristic of the element.
the mass number is the sum of the number of protons and neutrons. Since protons and neutrons both have similar masses and they are located in the nucleus, the mass of the atom is the sum of protons and neutrons.
Isotopes are when 2 atoms of the same element have different number of neutrons. Therefore atomic number is the same but mass number is different as the number of neutrons vary.

correct answer for the difference between isotopes is 
d)They have different numbers of neutrons and different mass numbers.

ANSWERED AT 06/12/2019 - 03:29 PM


QUESTION POSTED AT 06/12/2019 - 03:29 PM

Can show some work for 4x = -12

4x = -12

First, divide both sides by 4. / Your problem should look like: x =  -\frac{12}{4}
Second, since 4 goes into 3 to get 12, simplify it by 3. / Your problem should look like: x = -3

Answer: x = -3

ANSWERED AT 06/12/2019 - 03:28 PM


QUESTION POSTED AT 06/12/2019 - 03:28 PM