Hello,

After doing the Knewton assignments and watching some videos. I really do not understand some basics concepts of Energy. One of the questions is asking: Which of the following objects has more kinetic energy than does potential energy?

a) a compressed spring in a pinball machine just before the ball is launched.

b)a rollercoaster motionless at the top of the track.

c) a yo-yo before it is released

d)the pendulum of a grandfather clock at the lowest point of its arc of motion.

I thought that the answer was b, but the correct answer was c). I did not understand the explanation. It says " Kinetic energy is the energy of motion. Each of the objects above are motionless—with stored potential energy—except for the clock. At the bottom of its arc it will have the greatest kinetic energy, which is then converted to potential energy as it swings back up to one side"

So if someone could explain this better I would so good.

These are reactions that transfer energy to the surroundings (ie the energy exits from the reaction, hence the name exothermic). The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to become hotter. A thermometer is used to detect the temperature increase.

Examples:

Combustion

Neutralisation between acids and alkali

These are reactions that take in energy from the surroundings (ie energy enters the reaction, which will help you to remember the name endothermic). The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to become colder. A thermometer is used to detect the temperature decrease.

Example:

Electrolysis

Answer: see below

Explanation: for 75 ml, take 45*75 mg of BSA and make up to 75 mL with distilled water.

Answer:

CaCl2

Explanation:

The ionic solid CaCl₂ would have the largest lattice energy. Therefore, option (c) is correct.

Lattice energy is the heat of formation when one mole of crystalline ionic solid is generated from its constituent ions in their gaseous state.

For example, the lattice energy of sodium chloride crystal is the energy change of reaction when Na⁺ and Cl⁻ ions react to produce a NaCl crystal, which is equal to -786 kJ/mol.

The relation between lattice energy and lattice enthalpy at constant pressure is given by:

ΔU (lattice) = ΔH (lattice) - PΔV

Lattice energy is directly proportional to the charge on ions and inversely proportional to the interionic distance between ions.

For NaCl and NaF the charge on the ions is +1 and -1 while the size of the ions is small. So they have less lattice energy.

CsI ionic solid have a larger size of ions Cs⁺ and I⁻. So CsI will have less lattice energy. CsBr₂ has +2 charge on calcium but the size of both ios is larger. So, CsBr₂ will have less lattice energy.

CaCl₂ has + 2 charge on calcium as well as the ionic radius is also samll. Therefore, CaCl₂ would have the largest lattice energy.

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Answer:

becuase of the sun

in different places some places would be cold

Problem 1

The text (from the screenshot you posted) mentions that

"The atoms of covalent materials are bound tightly to each other in stable molecules, but those molecules are generally not very strongly attracted to other molecules in the material"

Put another way, we can think of each atom as a person, and each molecule as a family or a collection of persons. This is because any molecule is a collection of atoms. In covalent molecules, the connection between any two families isn't that strong since each person is focused more on their respective family, instead of other people outside the family. This is one way to think of it, but you may have a more effective way to remember.

In short, the exterior bonds between different covalent molecules isn't that strong, which means it's easier to break those bonds.

======================================================

Problem 2

The text also says

"The atoms (ions) in ionic materials show strong attractions to other ions in their vicinity"

This is due to the positively and negatively charged ions that attract to one another, and this causes a stronger chain so to speak. The stronger the chain, the harder it is to break when you apply temperature to it. Keep in mind that the only difference between a solid and a liquid is that the solid is a rigid structure while a liquid is more loose and free flowing. The ionic materials having a stronger inner bond like this is why ionic materials have higher melting points. You need to apply more temperature than normal to get the solid to melt.

======================================================

Problem 3

Again we turn to the text and it says

"For example, the molecule carbon tetrachloride is a non-polar covalent molecule, CCl4. It's melting point is -23 degrees Celsius. By contrast, the ionic solid NaCl has a melting point of 800 degrees Celsius"

In short, the difference between the two is that carbon tetrachloride has covalent bonds and NaCl (sodium chloride, aka table salt) has ionic bonds. It's much easier to melt the carbon tetrachloride than it is to melt the table salt.

Side note: carbon tetrachloride was historically used in fire extinguishers, but have been phased out due to safety concerns. Exposure to this toxin can lead to central nervous system problems, kidney failure, or liver problems. Due to its very low melting point, carbon tetrachloride is a liquid at STP.

1. Covalent compounds are held together by weak intermolecular forces. It is because of such weaker forces, which fails to make the compound bind tightly. Since lower heat (energy) is capable of breaking these weak intermolecular forces, therefore the melting and boiling points of covalent compounds is low.

2. Ionic compounds are held together by electrostatic forces between the oppositely charged ions . As the ionic lattice contains such a large number of ions, a lot of energy is needed to overcome this ionic bonding so ionic compounds have high melting and boiling points.

3. In terms of chemical bonding, carbon tetrachloride is a covalent chemical compound whereas sodium chloride is an ionic chemical compound. NaCl is solid in nature while CCl₄ is liquid.

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Answer:

B

Explanation: im not rlly sure you can go with what i said or you dont

Answer:

It is an example of ionic compound and ionic salt

Answer:

0.33%

Explanation:

From the question given above, the following data were obtained:

Experimental value = 9.842 m/s²

Accepted value = 9.81 m/s²

Percentage error =?

The percentage error in the calculation can be obtained as follow:

Percentage error = |Experimental – Accepted| / Accepted value × 100

Percentage error = |9.842 – 9.81| / 9.81 × 100

Percentage error = 0.032 / 9.81 × 100

Percentage error = 0.33%

Therefore, the error in the calculation is 0.33%

Answer:

Lithosphere, Hydrosphere, atmosphere

The set of Earth components that is arranged in order from solid to liquid to gas is D. lithosphere, hydrosphere, atmosphere

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Answer:

When a ball bounces, it initially gains speed or kinetic energy—the energy of motion. When it reaches Earth, it collides head-on with an incredibly massive object that is, from your perspective, at rest. The ball slows down, deforms temporarily and shoots back up.

Explanation:

I hope this helps.

Answer:

When you hold the ball in the air, the ball has gravitational potential energy. Realizing it will turn the potential energy into kinetic energy. When the ball touches the ground, the kinetic energy will turn into elastic potential energy. When it bounces back up, it will turn into kinetic energy. When the ball is in that position where the ball was being held, it will have gravitational potential energy and repeat the cycle.

Explanation:

Terms to know:

Gravitational potential energy is the energy of an object that possesses because of its position in a gravitational field.

Elastic potential energy is energy stored as a result of applying a force to deform an elastic object.

Kinetic energy is the energy that objects posess due to motion.

Answer:

6 all hope it helps thanks

Answer:

9.72 moles.

Explanation:

From the question given above, the following data were obtained:

Mass of H₂O = 175 g

Number of mole H₂O =?

Next, we shall determine the molar mass of H₂O. This can be obtained as follow:

Molar mass of H₂O = (2×1) + 16

= 2 + 16

= 18 g/mol

Finally, we shall determine the number of mole H₂O. This can be obtained as follow:

Mass of H₂O = 175 g

Molar mass of H₂O = 18 g/mol

Number of mole of H₂O =?

Mole = mass /Molar mass

Number of mole of H₂O = 175/18

Number of mole of H₂O = 9.72 moles

1.24 mol Cl2 x 6.022*10^23

=  7.47 Cl2 molecules

Hope that helps!

Answer:

1 mole of c12=6.022×10^23

so

1.24 mole of c12=1.24×10^23

Explanation:

according to the mole concept

no of mole is very important

if u have that given its very easy to do the solving

if not given go for the no of mole in mole concept for first

and always remember the constant (6.022×10^23) and formulae

A 57 grams sample of iron reacts with 24 grams of oxygen to form 81 grams of iron oxide.

Iron oxide is a chemical compound that is made by the addition of iron and oxygen can also be known as ferrous oxide if react with two oxygen molecules then ferric oxide.

In the sample, the iron is 57 grams and the oxygen is 24 grams,

                 Fe + O -------------> FeO

                Iron   oxygen            iron oxide

By adding the mass of iron and oxygen,

             57 + 24 = 81 grams of  iron oxide.

Therefore, the mass of iron oxide is 81 grams if 57 grams sample of iron reacts with 24 grams of oxygen.

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The question is incomplete, the complete question is;

A chemist prepares a solution of silver (I) perchlorate (AgCIO4) by measuring out 134.g of silver (I) perchlorate into a 50.ml volumetric flask and filling the flask to the mark with water. calculate the concentration in mol/L of the silver (I) perchlorate solution. Round your answer to 2 significant digits.

Answer:

13 mol/L

Explanation:

We must first obtain the number of moles of silver I perchlorate involved

Molar mass of silver I perchlorate = 207.32 g/mol

Number of moles of silver I perchlorate = 134g/207.32 g/mol = 0.646 moles

Recall that;

n =CV

C= concentration

V= volume

n = number of moles

C = n/V

C = 0.646 moles * 1000/50

C = 13 mol/L

Answer:

d

When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that we feel.

Answer:

bases taste bitter, feel slippery, and conduct electricity when dissolved in water

Explanation:

Answer:

like peas

Explanation:

Answer:

Natural gas

Explanation:

Natural gas is pretty clean when it burns compared to other gases.

Answer:

Explanation:

In all, an estimated 8,000 to 10,000 Iraqi forces were killed, in comparison with only 300 coalition troops. Though the Gulf War was recognized as a decisive victory for the coalition, Kuwait and Iraq suffered enormous damage, and Saddam Hussein was not forced from power.

hope this helps a lot!

Answer:

D

Explanation:

because it's so hot that it's almost to the point of changing to another element

Answer:

To be honest with you I think it is A or D

Explanation:

bc I said so

Answer:

B

Explanation:

Because unless you are walking towards it and the ocean is not moving then only you are moving

Answer:

full octets live in noble gas world so you need to be whatever your charge is away from there in steps on the periodic table so s-1 is the one that falls short as it is 2 moves away from Ar which is its closest Noble gas

Explanation:

Answer:

D.sandals

Explanation:

I think we need to wear shoes......so to protect or cover our feet

Answer:

False

Explanation:

Depends mostly on heating of the earths surface being uneven

It is false that global wind patterns have less to do with air temperature than local winds.

Local winds are those that blow over a small area. Local geography, such as proximity to an ocean, has an impact on them.

Monsoons and land and sea breezes are among them. Global winds occur in belts all over the world.

Temperature differences, particularly the difference in heating at the equator and poles, and the Earth's rotation determine the global atmospheric circulation pattern.

By transporting heat and water, winds shape regional climate and influence daily weather.

Global winds are winds that occur in belts that circle the globe. Global winds, like local winds, are caused by uneven heating of the atmosphere.

Because of the Coriolis effect, winds blow diagonally across the surface.

Thus, the given statement is false.

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6

Math

Pre-Algebra

Order of Operations: BPEMDAS

Chemistry

Stoichiometry

Step 1: Define

[RxN - Balanced] 2AgNO₃ (aq) + Cu (s) → Cu(NO₃)₂ (aq) + 2Ag (s)

Step 2: Identify

Reactants: 2AgNO₃ (aq) + Cu (s)

# of O atoms: 2(O₃) = 6 O