a. For a chemistry lab final exam, a high school chemistry student was given a 1-mole sample of CaCl2 and a 1-mole sample of MgCl2 but was not told which sample was which. He was to identify the powders.

He looked up the enthalpies of formation for both of the chemicals and calculated the ΔHreaction for dissolving each powder: CaCl2 (s) Ca 2+ (aq) + 2Cl – (aq), and MgCl2 (s) Mg 2 (aq) + 2Cl – (aq). He then put each powder in a coffee-cup calorimeter and added water.

When sample A dissolved, the temperature increased by 0.74°C. When sample B dissolved, the temperature increased by 0.39°C. Which chemical was A, and which was B? Use the table of enthalpies of formation to help you. Explain your reasoning.

Answer:

depth of the liquid and nature of liquid affects the pressure due to liquid contained in a vessel

Answer:

Two factors influence the pressure of fluids. They are the depth of the fluid and its density. A fluid exerts more pressure at greater depths

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The pressure in atm exerted by 1.8 g of H₂ gas exert in a 4.3 L balloon at 27ºC is 5.12 atm

The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).

Let's convert grams to moles (via molar mass).

Molar Mass (H₂) :  2 (1.008 g/mol)

Molar Mass (H₂) :  2.016 g/mol

1.8 grams H₂               1 mole

----------------------  x  ----------------------  =  0.893 moles H₂

                                2.016 grams

The Ideal Gas Law equation looks like this:

PV = nRT

In this equation,

After converting Celsius to Kelvin, you can put the given values into the equation and simplify to find the pressure.

P = ? atm                                R = 0.0821 L*atm/mol*K

V = 4.3 L                               T = 27 °C + 273.15 = 300.15 K

n = 0.893 moles

PV = nRT

P (4.3 L) = (0.893 moles) (0.0821 L*atm/mol*K)( 300.15 K)

P (4.3 L) =  22.0021

P = 5.12 atm

Therefore, The pressure in atm exerted by 1.8 g of H₂ gas exert in a 4.3 L balloon at 27ºC is 5.12 atm

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Answer:

im a just achild

Explanation:

Answer:

c

Explanation:

0.5dm³

follow me if you want

Answer:

337.5kPa ~ 338kPa

Explanation:

Using the ideal gas law PV=nRT we have the following definitions from the problem:

V(initial) = 20cm³

P(initial) = ?kPa

V(final) = 75cm³

P(final) = 90kPa

Since we know that the number of moles of the sample did not change, nor did the temperature, nor does the ideal gas constant (R) we can rewrite this equation to state:

P(initial)V(initial) = nRT =P(final)V(final) ~  P(initial)V(initial) = P(final)V(final)

Rearranging this equation as we are solving for the initial pressure we find that:

P(initial) = (P(final)V(final))/V(initial)

P(initial) = ((90kPa)(75cm³))/20cm³

P(initial) = 337.5kPa ~ 338kPA

Answer:

Explanation:

           The world is made up of ​living beings .    

Answer:

Explained below

Explanation:

In simple average, we just add all the given data variables and divide it by the number of data given.

However, when it comes to weighted average, what we do is that we multiply each given variable by their weights and then divide the sum of that by the sum of the weights.

Thus, if the variables are denoted by x and their weights are denoted by y, then we have;

Weighted average = Σ(xy)/Σy

Answer:

kinetic energy is the molecules

Explanation:

A molecule of the kind normally found in living systems. Organic molecules are usually composed of carbon atoms in rings or long chains, to which are attached other atoms of such elements as hydrogen, oxygen, and nitrogen.

Answer:

1. 3-methylpentane

2. 2-bromo-3-chloropentane

3. 2,2,4-trimethylpentane

Explanation:

1. CH3CH2CH(CH3)CH2CH3.

Methyl group is in the third carbon atom in the long chain. The organic compound has five(5) carbon atoms thus it is named as pentane.

Therefore the name of the compound is

3-methylpentane

2. CH3CH(Br)CH(Cl)CH2CH3

The compound has Chlorine and Bromine in the carbon chain. Chlorine is given as chloro-, Bromine is given as bromo, depending on the position in the carbon chain. Bromine is located in 2 carbon atom and chlorine is in third(3) carbon atom in the long chain. The long chain has five carbon atoms thus pentane.

Naming of the compound we begin with the on lowest in the alphabet. The name of the organic compound is therefore;

2-bromo-3-chloropentane

3. CH3CH(CH3)3CH(CH3)CH2CH3

In this long chained organic compound, methyl-group is found in 2,2 and 4th positions. Since this is still pentane, naming the organic compounds, we start with the one with the lowest carbon. Therefore this becomes;

2,2,4-trimethylpentane

I hope this helps you to know how to name the organic compounds.

Answer:

thank you for this oibnki

Answer:

Sure I'll go ahead and like your answers and follow you if that's what you wanted! :)

Explanation:

Answer:

0.94 L

Explanation:

The equation of the reaction is;

2LiOH + CO2 -----> Li2CO3 + H2O

Number of moles LiOH = 2.0/23.95 g/mol = 0.084 moles

2 moles of LiOH scrubs 22.4 L of CO2

0.084 moles of LiOH scrubs 0.084 moles × 22.4/2

= 0.94 L

Explanation:in testing for oxygen a glowing splint is used.

the glowing splint is brought in the presence of the test tube containing the gas

the glowing splint rekindles or lights up showing that oxygen is present.

this is a positive test because oxygen supports burning or combustion

Answer:

one atom of oxygen is not equal to oxygen

Answer:

The amount of acid rain caused by the burning of fossil fuels can be reduced by creating nitrogen oxides in the process of burning coal and other fossil fuels, some power plants are changing the way they burn coal. A great way to reduce acid rain is to produce energy without using fossil fuels. Instead, people can use renewable energy sources, such as solar and wind power.

Answer:

milk and starch solution are the colloids, hence these will show the tyndall effect

Answer:

milk and starch solution

Explanation:

Tyndall effect is shown by colloidal solutions. It is not shown by true solutions or suspensions.

Milk and starch solution are colloidal solutions. They show tyndall effect. On the other hand, common salt and copper sulphate solution are true solutions. They do not show tyndall effect.

Answer:

all of this

Explanation:

i) Be has a fully filled 2s level.

ii) This is because chlorine is larger than fluorine.

iii) Fluorine needs only one electron to attain the octet configuration.

Electron affinity is the ability of an electron to accept  gaseous electrons to yield gaseous ions with a negative charge.  

Electron affinity depends on the size of an atom. Larger atoms have a higher electron affinity because they are better able to accept electrons.

The drop between Li and Be is because the 2s orbital in Be is already fully filled while Li has incompletely filled 2s level. electrons do not easily go into the higher energy 2p level.

The higher peak of chlorine is because chlorine is larger than fluorine hence the electron affinity of fluorine is less than that of chlorine. The smaller the ion the lesser the electron affinity.

Fluorine has the highest electron affinity in period 2 because it needs only one electron to attain the octet structure.

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The Answer is A)4 atoms of NA are present in 92 a.m.u

Answer:

Scientists must look in their experiment/data to check for accuracy because they don't want to make any mistakes, and most importantly have to make sure they have the right information to proceed.

Explanation:

^

If I could change something in my previous science classes, it would have been the fact that I struggled in the question concerning exponents. It was simple one, but I don't know how I didn't understood that. For example, if there is a question with a calculation "xy²", then I would first multiply x and y, and then calculate the exponent. I did 3 of the questions wrong because of this, it was when I was in 7th grade. I wish I had not done this kind of silly mistake. I an in 10th grade and understand it well now, though.

Answer:

Joule is the SI unit of work. 1 Joule is amount of work done when a force of 1 Newton displaces a body through a distance of 1m in the direction of the force applied.

Answer:

The molar mass of the compound given is 182.182 g/mol.

Explanation:

To calculate the molar mass of the compound, we must multiply the number of moles of each element by the the individual molar mass of each element and add them together.

Let's start with Calcium.  The molar mass of Calcium is 40.078.  In this compound, we have three moles of Calcium, so we should multiply this number by 3.

40.078 g/mol * 3 mol = 120.234 g

Now, let's do the same for Phosphorus.

30.974 g/mol * 2 g/mol = 61.948 g

To find the molar mass of the entire compound, we should add these two values together.

120.234 g + 61.948 g = 182.182 g

Therefore, the correct answer is 182.182 g/mol.

Hope this helps!

The volume of a gas at 6.0 atm is 2.5 L. What is the volume of the gas at 7.5 atm at

the same temperature? (5 points)

1) 1.0 L

2) 1.5 L

3) 2.0 L

4) 3.0L

Answer:

2.0 L

Option C) 2.0L is the correct answer.

Hence, at the same temperature, as the pressure is increased to the given value, the volume of the gas decreases to 2.0L.

Boyle's law

Boyle's law states that "the volume V of a given quantity of gas is inversely proportional to its pressure P as long as temperature remains constant.

Boyle's law is expressed as;

P₁V₁ = P₂V₂

Given the data in the question;

To determine the final volume of the gas, we substitute our given values into the expression above.

P₁V₁ = P₂V₂

V₂ = P₁V₁ /  P₂

V₂ = ( 6.0atm × 2.5L ) /  7.5atm

V₂ = 15Latm / 7.5atm

V₂ = 2.0L

Option C) 2.0L is the correct answer.

Hence, at the same temperature, as the pressure is increased to the given value, the volume of the gas decreases to 2.0L.

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Answer:

Winter

Explanation:

I dont know but whatev

Answer:

Winter

Explanation:

The seasonal cycle in the polar and temperate zones of one hemisphere is opposite to that of the other. Therefore, When it is summer in the Northern Hemisphere, it is winter in the Southern, and vice versa.

hope it helps :)

Answer:

A body becomes weightless in a zero-gravity scenario and when a force is applied to a body that is equal and opposite to the force of gravity. If the body is falling only under the influence of gravity.

Answer:

A body becomes weightless in a zero-gravity scenario and when a force is applied to a body that is equal and opposite to the force of gravity.If the body is falling only under the influence of gravity.

Answer:

B.electrostatic repulsion by gold nuclei

Explanation:

According to Rutherford's experiment, a thin gold foil was bombarded with alpha particles. Some of the particles passed through the foil undeviated, some were scattered through large angles while some bounced backwards.

It follows that the particles that bounced backwards must have encountered a massive particle of like charge.

The atom is composed of a nucleus which contains positively charged particles. Some of the alpha particles which are positively charged particles bounced back when they encountered the positively charged particles in the nucleus.

Answer: The correct option is B (electrostatic repulsion by gold nuclei).

Explanation:

In the Rutherford's experiment, he used positively charged particles called alpha particles to bombard an atom in order to find out what is inside the atom. Together with two other scientists, Geiger and Marsden, they used a narrow beam of alpha particles emitted from a radioactive source to bombard a thin gold foil. The scattering of the particles from the gold foil was detected by a movable zinc sulphide screen which could be rotated to various positions around the foil.

Each time an alpha particle hit the screen, a visible flash of light or scintillation was produced. This was observed by a microscope attached to the screen. It was then observed that some of the particles followed a straight path through the gold foil while a few where scattered in a backward direction. This was as a result of electrostatic repulsion by gold nuclei which occurs due to the greater part of the mass of the atom was concentrated in a minute nucleus with positive charge.

Answer:

chắc là câu B í

Explanation:

Answer: B

Explanation:

Answer:

The Correct Answer Is B.