A student mixed two chemicals to allow them to
react. The temperature before the reaction was 25
°C. The temperature after the reaction was 50° C.
Which of the following is true?
A. there was no change in heat energy
B. it is an exothermic reaction

help plsssss

Answers

Answer 1

Answer:

B .it is an exothermic reaction

Explanation:

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Related Questions

WILL MARK BRAINLIST!
A chemist needs 32.0 g of phenol, C6H5OH, for an experiment. How many moles of phenol is this?
Explain how to find the molar mass of the compound.
Explain how many significant figures your answer needs to have.
The numerical answer

Answers

A chemist needs 32.0 g of phenol, for an experiment. The number of moles of phenol is 0.340 mol.

What are moles?

The mole is a SI unit of measurement that is used to calculate the quantity of any substance.

Calculating the moles

[tex]\rm Number\;of \;moles= \dfrac{mass}{molar\;mass}\\\\\rm Number\;of \;moles= \dfrac{32.0}{94.11} = 0.340 moles[/tex]

The molar mass can be calculated by counting the molecules of the elements. Then multiply the molecules of each element with its molar mass and then add the total number, you'll get the molar mass of the compound.

Thus, the number of moles of phenol is 0.340 mol.

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Name these compounds according to IUPAC. (ASAPP)

Answers

The chemical's IUPAC names of the given compound are propanal and acetone.

What is IUPAC naming?

IUPAC is the international union of practical and applied chemistry. It set rules for standard naming of the compound.

Propanal, or propanaldehyde, is an aldehyde that has one double bond and one oxygen atom.

Acetone is a kind of ketone. Ketones have the functional group R2CO.

Thus, chemical's IUPAC names of the given compound are propanal and acetone.

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How many grams of C8H18
is in 405,576.398 mL

Answers

[tex]Molarity X \frac{0.762 mol}{05.576398 L} = Mass[/tex] is the of [tex]C_8H_1_8[/tex] is in 405,576.398 mL.

What is molarity?

Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per litres of a solution. Molarity is also known as the molar concentration of a solution.

Given data:

Molar mass of  [tex]C_8H_1_8[/tex] = 0.762 mol

Volume of solution = 405,576.398 mL = 405,576.398 mL/1000 = 405.576398 L

Solution:

Step 1: Calculating  moles of [tex]C_8H_1_8[/tex]

• Molarity =[tex]\frac{\;Moles \;of \;solute}{\;Volume \;of \;solution \;in \;litre}[/tex]

• Putting the value in the given formula

• Moles of solute C8H18 = [tex]\frac{\;Mass}{\;Molar \;molar \;mass}[/tex]

• Moles of solute C8H18 = [tex]\frac{\;Mass}{0.762 mol}[/tex]

Now,

Molarity =[tex]\frac{\;Moles \;of \;solute}{\;Volume \;of \;solution \;in \;litre}[/tex]

Molarity =[tex]\frac{\frac{\;Mass}{0.762 mol}}{\;Volume \;of \;solution \;in \;litre}[/tex]

Molarity =[tex]\frac{\frac{\;Mass}{0.762 mol}}{405.576398 L}[/tex]

[tex]Molarity X \frac{0.762 mol}{05.576398 L} = Mass[/tex]

Hence, [tex]Molarity X \frac{0.762 mol}{05.576398 L} = Mass[/tex] is the of [tex]C_8H_1_8[/tex] is in 405,576.398 mL.

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1. What is a taste bud?
O tissues containing nerve cells for taste
another name for the tip of the tongue
O
a liquid in the mouth that breaks down food
O a molecule that allows you to taste food

Answers

O tissues containing nerve cells for taste

WILL GIVE BRAINLIEST

If an element is in period 6, what is the highest possible number of electrons that can be in that atom?

Answers

72 is the electron capacity for period 6

In a spontaneous fission reaction, the total mass of the products is _______________ the mass of the original elements.

Answers

Explanation:

is equal to the mass of the original elements

Which scientist provided a foundation for John Dalton’s work on the atomic structure?
Robert Millikan
Joseph Proust
Ernest Rutherford
J. J. Thomson

Answers

Answer:

J.J. Thomson

Explanation:

Answer:

D

Explanation:

took the test

Complete the sentence using the word refracting, radlo, or space.
Telescopes that use lenses to bend light are called
telescopes.

Answers

Answer:

Refracting

Explanation:

Mark the word bend lightHence light travels through one medium to another it bends down which is called refraction.The bendness depends upon the refractive index of medium.

Which shows an isomer of the molecule below?

Answers

The isomer of the molecule in the depicted image would be A.

What are isomers?

Isomers are molecules with the same chemical formula but different arrangements of their component atoms. Isomers also have different properties.

The original molecule in the image has a triple bond with 4 carbon atoms. Thus, its isomers must also have a triple bond with 4 carbon atoms.

The only option with a triple bond and 4 carbon atoms in the image is option A.

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81. Predich Describe what might happen if you put a sealed glass container full of water into a freezer.

Answers

Answer:

When liquid water reaches the freezing point, it expands. After placing a sealed glass container full of water into the freezer, we might expect it to freeze, expand, and either crack or shatter the glass.

Explanation:

Identify the acid, base, conjugate acid, and conjugate base in the following reaction:
HSO4- + NH3 = SO4-2 + NH4+

Answers

Answer:

Acid: HSO4-

Base: NH3

Conjugate Acid: NH4+

Conjugate Base: SO4-2

Explanation:

HSO4- gives a H+ to NH3 making NH4+ the conjugate acid.

Same can be said to the base.

Which statement describes what happens when somebody slaps their hand on a wall?

Answers

Answer:

B. Wall applies equal reaction force on hand

Explanation:

This is newton's third law. You push something, that something pushes you back with same force. The direction is opposite, so if I push a wall, the wall pushes me back with same force just in opposite direction (so wall towards me). This is why option A is incorrect b/c it says force in same direction as wall. C and D talk about unequal force which is incorrect.

Answer:Wall applies equal reaction force on hand

Explanation:

What is the poh in a solution if the [oh-] = 5.42 x 10-5 m?

a
5.26

b
7.26

c
4.26

d
6.26

Answers

Answer:

b

Explanation:

is the dictionary definition of a word.

is the feeling or idea associated with a word.

Lewis dot structure for H2CCCl2?

Answers

Answer:

Explanation:

lewis dot structure:

Carbon has 4 valence electrons and hydrogen has 1 electron. Therefore, in below given way, the lewis dot structure for H[tex]_2[/tex]CCCl[tex]_2[/tex] can be drawn.

What is Lewis dot structure?

These illustrations, commonly referred to as lewis structures and electron dot structures, show how electrons are distributed and grouped around atoms.

You must be aware of the total amount of valence electron cloud in order to create the Lewis structure. Based on the atom's group number inside the periodic table, it is possible to determine how many valence electrons are present in a certain atom. Carbon has 4 valence electrons and hydrogen has 1 electron. The lewis dot structure for  H[tex]_2[/tex]CCCl[tex]_2[/tex] is given below.

Therefore, in above given way, the lewis dot structure for H[tex]_2[/tex]CCCl[tex]_2[/tex] can be drawn.

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Name these compounds according to IUPAC.

Answers

The name of the compound CH₃CHOOH is acetic acid.

What is IUPAC naming rules?

The International Union of Pure and Applied Chemistry (IUPAC) names organic compounds according to chemistry rules.

To locate the longest carbon chain, there are various requirements to follow, such as finding the functional group.

Thus, the name of the compound CH₃CHOOH is acetic acid.

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A balloon containing 0.15mol of hydrogen gas (H2) has a volume of 0.75L. If the balloon is further inflated with additional hydrogen gas to a 3.75L volume, what is the total mass of hydrogen gas in grams in the balloon

Answers

The total mass of hydrogen gas in grams in the balloon given the data is 1.5 g

How to determine the new mole of hydrogenInitial mole (n₁) = 0.15 moleInitial volume (V₁) = 0.75 LNew volume (V₂) = 3.75 LNew mole (n₂) = ?

The new mole of the gas can be obtained by using the ideal gas equation as follow:

PV = nRT

V / n = RT / P

RT / P = constant

V₁ / n₁ = V₂ / n₂

0.75 / 0.15 = 3.75 / n₂

5 = 3.75 / n₂

Cross multiply

5 × n₂ = 3.75

Divide both sides by 5

n₂ = 3.75 / 5

n₂ = 0.75 mole

How to determine the mass of hydrogenNumber of mole = 0.75 moleMolar mass of H₂ = 2 g/moleMass of H₂ = ?

Mass = mole × molar mass

Mass of H₂ = 0.75 × 2

Mass of H₂ = 1.5 g

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How much of a 500g sample of potassium-42 is left after 37.2 hours if the half-life of potassium-42 is 12.4 hours

Answers

Answer:

15.625 g of  a 500 gram sample of potassium-42 with 12.4 hours of Half -life is left after 62 hours.

The half-life is the time after which half of the initial quantity of a radioactive substance is left .

Given here,  

The half-life of K-42 = 12.4 hours  

The initial quantity of K-42 = 500 gm  

The final quantity after 62 hours = ?  

The number of half cycle

 

Thus the number of half life cycles in 62 hours is 5,

After 1 half life  

After 2 half lives  

After 3 half lives  

After 4 half lives    

After 5 half lives  

15.625 g of  a 500 gram sample of potassium-42 with 12.4 hours of Half -life is left after 62 hours.

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If a gas has a volume of 350 mL at 780 mm Hg, what pressure will be needed to cause its volume
to be 500 mL?
Could you state the law used?

Answers

The required pressure of the gas is 546 mmHg.

What is the relation between volume and pressure?

Relation between the volume and pressure of gas is explained through the ideal gas equation PV = nRT, and for the question required equation is:

P₁V₁ = P₂V₂, where

P₁ & V₁ are the initial pressure and volume.

P₂ & V₂ are the final pressure and volume.

On putting values from the question to the equation, we get

P₂ = (780)(350) / (500) =

P₂ = 546 mmHg

Hence required pressure is 546 mmHg.

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What is the molarity of a solution of h3po4 if 10.2 ml is neutralized by 53.5 ml of 0.20m koh what is the molarity of a solution of h3po4 if 10.2 ml is neutralized by 53.5 ml of 0.20m koh 0.67m h3po4 0.15m h3po4 0.35m h3po4 0.37m h3po4

Answers

The molarity of the solution of H₃PO₄ needed to neutralize the KOH solution is 0.35 M

Balanced equation

H₃PO₄ + 3KOH —> K₃PO₄ + 3H₂O

From the balanced equation above,

The mole ratio of the acid, H₃PO₄ (nA) = 1The mole ratio of the base, KOH (nB) = 3

How to determine the molarity of H₃PO₄ Volume of acid, H₃PO₄ (Va) = 10.2 mLMolarity of base, Ca(OH)₂ (Mb) = 0.2 MVolume of base, Ca(OH)₂ (Vb) = 53.5 mL Molarity of acid, H₃PO₄ (Ma) =?

MaVa / MbVb = nA / nB

(Ma × 10.2) / (0.2 × 53.5) = 1 / 3

(Ma × 10.2) / 10.7 = 1 / 3

Cross multiply

Ma × 10.2 × 3 = 10.7

Ma × 30.6 = 10.7

Divide both side by 30.6

Ma = 10.7 / 30.6

Ma = 0.35 M

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How many grams of BaCl2 are required to make 1.50L of a 0.60M solution?

Answers

Answer:

187.407g

Explanation:

Moles of solute = Molarity × Liters of solution

Multiply 0.60 M by 1.50L:

0.60 mol/ 1L×1.50L=0.9 mol

To obtain the mass of solute, we will need to the molar mass of BaCl2, which is 208.23g/mol:

Finally, multiply the number of moles by208.23g /mol

0.9mol×208.23g/1mol =187.407g

Boom, you have a mass of:

187.407g

m=n.M
We have C=0.60M, V=150L, M[BaCl2]=208g/mol
—>n=CxV = 0.60x1.50=0.9mol
So m= 0.9x208=187.2gram

A lunar eclipse occurs when the Moon casts a shadow on the Earth.

Answers

Answer:

No....see below

Explanation:

Well not quite.... that would be a solar eclipse....when the Earth shadows  the moon from the Sun is a lunar eclipse

What will most likely happen when stress is applied to an equilibrium reaction?
A) The system will not respond to the stress.
B) The system will use catalysts to change its equilibrium.
C) The equilibrium position will shift to increase the applied stress.
D) The system will change its concentration to shift to a new equilibrium position.

Answers

Answer:

option D is the correct answer of this question.

When stress is applied to an equilibrium reaction then the system will change its concentration to shift to a new equilibrium position.

So, the correct option is D.

What is equilibrium ?

The stage at which the rate of formation of reaction is equal to rate of backward reaction in an reversible reaction is called equilibrium.

The reaction in such stage occur is called equilibrium reaction.

Factors affecting equilibrium reaction.

There are some factors which affects the equilibrium.

Pressure : On increasing pressure of the gas present in reactant side shift the reaction to forward direction.Concentration : As concentration of the reactant increases then the reaction shifts in forward direction and as concentration of product is increases then the reaction moves in backward directionTemperatureNumber of moles.

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What property of copper makes it ideal to create thin sheets of
copper?

Answers

Copper is a soft, ductile, and malleable metal that bends and stretches easily without breaking. Copper is a versatile metal for construction and manufacturing because of this.

1. What makes a "fluorescent" highlighter marker so bright?

2. How does plasma make a campfire flame orange?

3. Why are crystals rare?

Answers

Answer:

1. What makes a "fluorescent" highlighter marker so bright?

When light of a certain wavelength is directed at the molecule's chromophore, a photon is absorbed and excites an electron to a higher energy state. Fluorescent highlighter ink is unusually bright because it converts some of the incident ultraviolet light that is invisible to humans into visible light.

2. How does plasma make a campfire flame orange?

The de-excitation of plasma (charged gas) is not the source of the light given off by a campfire's flame. The incandescence of solid soot particles billowing up on an updraft of hot air is what creates the light seen as a flame.

3. Why are crystals rare?

The answer is twofold: erosion and mixed composition. Wind, rain, and water flow have a way of knocking and mixing around things here on earth

Answer:

1: When light of a certain wavelength is directed at the molecule's chromophore, a photon is absorbed and excites an electron to a higher energy state. Fluorescent highlighter ink is unusually bright because it converts some of the incident ultraviolet light that is invisible to humans into visible light.

2: The de-excitation of plasma (charged gas) is not the source of the light given off by a campfire's flame. The incandescence of solid soot particles billowing up on an updraft of hot air is what creates the light seen as a flame.

3: erosion and mixed composition. Wind, rain, and water flow have a way of knocking and mixing around things here on earth. This erosion causes big crystals such as a palm-sized amethyst to get knocked apart into little crystals.

If a gas is compressed from 4L to 1L, and the temperatures remained constant, what happens to the pressure?

Answers

According to Gay lussac's law

[tex]\\ \rm\Rrightarrow P\propto T[/tex]

Pressure is directly proportional to temperatureTemperature is constant so no use of this

But according to Boyles law

[tex]\\ \rm\Rrightarrow P\propto \dfrac{1}{V}[/tex]

If volume is decreased by 4 times then pressure is increased by 4times

2AlCl3 → 2Al + 3Cl2

In the reaction above, if we were to get 7.50g of AI, what would be the yield of the experiment.

Answers

Answer:

Explanation:

2AlCl3 → 2Al + 3Cl2

In the reaction above, if we were to get 7.50g of AI, what would be the yield of the experiment.

HELP PLEASE ASAP WILL MARK BRAINLIEST


what is the amount of heat required to raise the temperature of 200.0g of aluminum by 10C (specific heat of aluminum: 0.21 cal/g C)

a. 420 cal
b. 4200 cal
c. 42,000 cal
d. 420,000 cal


Please show calculations!

Answers

m=200g∆T=10°C

Now

[tex]\\ \rm\Rrightarrow Q=mc\delta T[/tex]

[tex]\\ \rm\Rrightarrow Q=200(10)(0.21)[/tex]

[tex]\\ \rm\Rrightarrow Q=20(21)[/tex]

[tex]\\ \rm\Rrightarrow Q=420cal[/tex]

Answer:

AAAAA its A

Explanation:

. Given the balanced equation representing a reaction:
Fe(s) + 2HCl(aq) → FeCl₂ (aq) + H₂(g)
This reaction occurs more quickly when powdered
iron is used instead of a single piece of iron of the
same mass because the powdered iron
A) acts as a better catalyst than the single piece of
iron
B) absorbs less energy than the single piece of iron
C) has a greater surface area than the single piece of
iron
D) is more metallic than the single piece of iron

Answers

Answer:

C

Explanation:

The powdered iron has a greater surface area than the single piece of metal, allowing reactions to be done faster.

It's NOT A because in the reaction Iron is a reactant NOT a catalyst

It's NOT B because it's completely irrelevant to the question

It's NOT D because it's also not relevant to the question at hand

which of the following chemical symbol is that of an element with six electrons in the outermost shell a)Ca b)Cl c)Ne d)S​

Answers

hey there!

Sulphur is the element which has 6 electrons in the outermost shell.

WhereasCalcium,Neon have 2 and chlorine has 7.

Hope this explanation helps you :)
Have a good day :)

Answer:

S

Explanation:

Using periodic table (see those little numbers in the upper right?  Those are electron 'shells' .... look at the bottom one)

Ca has 2     Cl has 7       Ne has 8        S  has 6 in the outermost shell

in need of some help with this question please~

when 4g of oxygen gas reacts with excess of hydrogen gas, the volume of water vapour produced at (STP) is ....... L ( H = 1 , O = 16).

a) 22.4
b) 44.8
c) 11.2
d) 5.6

an explanation would be great for future reference <3 thank you in advance!

Answers

Answer:

5.60 Liters at STP

Explanation:

First you need the balanced reaction equation

2 H2 +  O2   ====>   2  H2O

4 g of oxygen ( O2 )  is   4/(15.999*2) moles of O2     (using periodic table)

  Twice the number of moles of H2O re produced   (from equation)

     at STP the volume of a mole of gas is 22.4 liter/ mole

       put all of this together  

         2 *   4 / (15.999*2) moles * 22.4 L/mole = 5.60 L

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