Which is a definite sign of a chemical reaction?

Chemical properties change.

Physical properties change.

A gas forms.

A solid forms

Answers

Answer 1

Answer: here i am choosing two answer because i am not sure . a gas forms and a solid forms

Explanation: a solid forms thus is to say a precipitate is formed

a gas forms thus to say effervescence , fizzing and bubbling whiles a gas is being produced.


Related Questions

How many joules of heat are needed to raise the temperature of 62.0 g of ethylene glycol from 13.1 C to 40.5C?

Answers

Answer:

Q = 4133.2 J

Explanation:

Hello there!

In this case, since these calorimetry problems are based off the following heat equation involving heat (Q), mass (m), specific heat (C) and temperatures (T):

[tex]Q=mC(T_2-T_1)[/tex]

Thus, we plug in the given variables to obtain:

[tex]Q=62.0 g*2.433 \frac{J}{g\°C}* (40.5\°C-13.1\°C)\\\\Q=4133.2J[/tex]

Regards!

Hydrogen gas can be produced in the laboratory by the reaction of magnesium metal with hydrochloric acid, according to the following equation:
Mg(s) + 2HCl(aq) --> MgCl2(aq) + H2(g)

a. How many grams of hydrogen can be produced when 4.00 g of HCl is added to 3.00 g of Mg?

b. Assuming STP, what is the volume of this hydrogen?

Answers

Answer: 0.11 g H2

Explanation: just took test and got it right

Given a solution with a hydrogen ion concentration of 9.9 x10-13 M, calculate the
pОН. .

Answers

Answer: The pOH value is 2.

Explanation:

Given: [tex][H^{+}] = 9.9 \times 10^{-13} M[/tex]

pH is defined as the negative logarithm of hydrogen ion concentration.

Hence, pH of the given solution is calculated as follows.

[tex]pH = -log [H^{+}]\\= - log (9.9 \times 10^{-13})\\= 12[/tex]

The relation between pH and pOH is as follows.

pH + pOH = 14

Therefore, pOH is calculated as follows.

pH + pOH = 14

12 + pOH = 14

pOH = 14 - 12

= 2

Thus, we can conclude that the pOH value is 2.

(reporting links) brainly
Amebic dysentery is a disease caused by organisms that live in dirty water. Which is most likely to prevent an epidemic of amebic dysentery?


A. vaccination of the population

B. purification of drinking water

C.public education on the importance of washing hands

D.restriction on travel to places with amebic dysentery

Answers

Answer:

The answer would have to be public education on the importance of washing hands.

Explanation: Washing hands is always one of the best ways to prevent a contagious disease.

A balloon contains 25.0 L of helium gas at 177 kPa. What is the volume when the balloon rises to an altitude where the pressure is only 43.0 kPa ? Assume the temperature remains constant.

A.34.2 L
B.68.8 L
C.46.5 L
D.103 L

Answers

I think answer is D not sure

Give examples of how land resources are used in a city setting

Answers

Answer:

Land resources such as gravel and bedrock are used to construct buildings, roads, and sidewalks. Land is also where city structures—such as buildings, roads, and sidewalks—are constructed. People use land resources such as bedrock and aggregate to construct buildings, roads, and sidewalks.

I hope this answer helps

Name the process by which oxygen moves from alveoli to blood

Answers

diffusion...........the blood through the capillaries lining the alveolar walls. Once in the bloodstream, oxygen gets picked up by the hemoglobin in red blood cells.

5. How would you calculate the pH (NOT POH) of a base when given

the concentration of [OHJ?

Answers

Answer:

pOH = -log₁₀ [OH-]

pH = 14 - pOH

Explanation:

First of all, calculate the value of pOH from  the hydroxide concentration do this using the equation below;

pOH = -log₁₀ [OH-]

After obtaining the pOH, calculate pH using the equation below:

pH + pOH = 14

pH = 14 - pOH

True or False: When it is spring in the Northern Hemisphere, it is autumn in the Southern Hemisphere.

Answers

Answer:

That is true

Explanation:

Concerning the disposal of materials at the end of the experiment, which methods are safe? Check all that apply.


[ANSWERS]


B. Dispose of pH paper in the trash.


C. Dump the cabbage indicator solution down the drain.


D. Ask your teacher to neutralize the acids and bases before disposal.

Answers

Answer:

B. Dispose of pH paper in the trash.

C. Dump the cabbage indicator solution down the drain.

D. Ask your teacher to neutralize the acids and bases before disposal.

Explanation:

Safe disposal of waste means disposal of waste in such a way that it does not pose a threat to the environment.

When pH paper is properly disposed in the trash, it does not constitute any risk to the environment.

When a cabbage indicator solution is disposed down the drain it does not contaminate the environment. It moves directly into the sewers and is properly disposed.

When acids and bases are properly neutralized before disposal, they don't lead to acid or base contamination of the environment.

Each element emits its own unique wavelength of light which can be used to determine the identity of that element. The packet or light wave emitted is called a

Answers

Answer:

Photon

Explanation:

The simplest description of a photon is to consider it as a bundle of electromagnetic energy.

In the context of wave - particle duality, light is considered sometimes as a particle. Each bundle of the particles of light wave is called a photon of light.

The wavelength of a photon of light emitted by an element can be used as a tool to identify that particular element.

1. What is the new volume of a sample of neon if 5.23 L of the gas, which was originally at 214 mmHg, is compressed until the pressure increases to 796 mmHg?
2. When a balloon containing 635 mL of air is taken from sea level (at standard pressure) to a higher altitude, the balloon expands to 829 mL. What is the air pressure at this new altitude (in atm)?
3. A 465 mL sample of gas at 55°C is cooled to standard temperature (0°C). What is its new volume?
4. To what Celsius temperature does 750. mL of gas originally at −12°C need to be heated to bring the volume to 2.10 L?
5. The pressure in a car tire is 217 kPa at 24°C. After being driven on a hot summer day, the pressure in the tire increases to 258 kPa. What is the Celsius temperature of the air in the tire?
6. A gas sample originally at −39°C is heated to standard temperature (0°C), at which point its pressure is measured to be 808 mmHg. What was the original pressure of the gas?
7. A 400. mL sample of gas at 15°C and 113 kPa is heated to 227°C while expanding into a 900. mL container. What is the new pressure of the gas in kPa?
8. 2.50 g of CO2 gas is confined in a rigid cylinder at a pressure of 4.65 atm. If 0.42 g of gas is released from the cylinder, what is the new pressure?
Please help I'm so bad at chemistry

Answers

Here are attached photos, I don’t think they ar links, lmk if they don’t work

in the answering section it didn’t show me the full question so I only saw a little of question 5. Hopefully you get the idea of how to identify which equations to use tho! Good luck!

Balloon has a volume of 600-ml at temperature of 360 K. If the temperature of
the balloon drops to 250 K, find the volume

Answers

Answer:

V₂ ≈416.7 mL

Explanation:

This question asks us to find the volume, given another volume and 2 temperatures in Kelvin. Based on this information, we must be using Charles's Law and the formula. Remember, his law states the volume of a gas is proportional to the temperature.

V₁ / T₁ = V₂ / T₂

where V₁ and V₂ are the first and second volumes, and T₁ and T₂ are the first and second temperature.

The balloon has a volume of 600 milliliters and a temperature of 360 K, but the temperature then drops to 250 K. So,

V₁= 600 mL T₁= 360 K T₂= 250 K

Substitute the values into the formula.

600 mL /360 K = V₂ / 250 K

Since we are solving for the second volume when the temperature is 250 K, we have to isolate the variable V₂. It is being divided by 250 K. The inverse o division is multiplication, so we multiply both sides by 250 K.

250 K * 600 mL /360 K = V₂ / 250 K * 250 K 250 K * 600 mL/360 K = V₂

The units of Kelvin cancel, so we are left with the units of mL.

250 * 600 mL/360=V₂416.666666667 mL= V₂

Let's round to the nearest tenth. The 6 in the hundredth place tells us to round to 6 to a 7.

416.7 mL ≈V₂

The volume of the balloon at 250 K is approximately 416.7 milliliters.

1) Escribe oraciones coherentes que incluyan los siguientes términos con los conceptos correspondientes:

CARBÓN-PETRÓLEO-GAS NATURAL-RECURSO NO RENOVABLE-

COMBUSTIBLES FÓSILES-HIDROCARBUROS-RESERVAS-CONTAMINACIÓN-

MAREAS NEGRAS

Answers

La respuesta correcta para esta pregunta abierta es la siguiente.

Estas son las oraciones apropiadas.

El carbón, el petróleo, y el gas natural son recursos naturales no renovables.

Estos generadores naturales de energía son considerados combustibles  fósiles que produce la mayor parte de hidrocarburos que se usan en el mundo. Sin embargo, estas reservas energéticas se están agotando porque son recursos naturales no renovables. Además, estos combustibles son altos generadores de contaminación como es el caso de las mareas negras.

Independientemente de estas ideas, es apropiado decir que los combustibles fósiles han sido fuertemente cuestionados por los ambientalistas y los científicos porque son causantes del llamado calentamiento global y del cambio climático.

Por esa razón, la sociedad y los expertos ambientalistas están pidiendo que los gobiernos comiencen a utilizar más energías alternativas y renovables como la energía solar y las turbinas de viento o energía eólica.

Which of the following is an example of a molecular element?

a.NaCl b. CO2 c. Na d. O2

Answers

Answer:

oxygen (O2) is a molecular element

Explanation:

Molecular compound are chemical compounds that take the form of discrete molecules.

atomic element is an element which occurs independently as atoms and can react with other elements to form a compound

Ionic compounds are the compound which on dissolution form ions in solution

Mixture is the composition of different compounds

which process is a chemical change​

Answers

Burning a match, In chemistry, there are two basic types of change, these are physical and chemical change. In physical change, no new material is formed and the process is reversible while in chemical change new materials are formed and the process is irreversible

Iodine-131 half life 8.040 how long will it take for a 40 gram sample of iodine-131 to decay to 0.75 grams

Answers

Answer:

See explanation below

Explanation:

To get this, we need to apply the general expression for half life decay:

N = N₀e(-λt)    (1)

Where:

N and N₀ would be the final and innitial quantities, in this case, masses.

t: time required to decay

λ: factor related to half life

From the above expression we need λ and t. To get λ we use the following expression:

λ = t₁₂/ln2   (2)

And we have the value of half life, so, replacing we have:

λ = 8.04 / ln2 = 11.6

Now, we can replace in (1) and then, solve for t:

0.75 = 40 exp(-11.6t)

0.75 / 40 = exp(-11.6t)

ln(0.01875) = -11.6t

-3.9766 = -11.6t

t = -3.9766 / -11.6

t = 0.34 days

What product is formed when sodium and chlorine undergo a synthesis reaction? sodium chlorite
sodium chlorate
sodium and chloride
sodium chloride

Answers

Sodium chloride is the answer
Sodium chloride is formed

Select all of the HOMOGENEOUS mixtures from this list (click all that apply).

A. Paint
B. Chili
C. Blood
D. Soil
E. Salt water

Answers

Answer:

E is answer

Explanation:

salt water is the answer

Answer:

E.Salt water

Explanation:

Salt water  is  a homogeneous because the dissolved salt is evenly distributed throughout the entire salt water sample. The amount of salt in the salt water can vary from one sample to another.

Hot water is poured into four cups made of different materials (foam, glass, metal, plastic).After one minute, which will feel the warmest when you touch the OUTSIDE of the cup?

Answers

The answer to this is metal

Answer:

Metal

Explanation:

Foam, glass, and plastic don't absorb as much heat as metal does.

1. If you have 8.1 g CO₂ and 2.3 g H₂, which one is the limiting reactant. Show your work. 2. Calculate the theoretical yield of CH₄.

Answers

Answer:

2.95 g of CH₄

Explanation:

To start this, we determine the equation:

4H₂  + CO₂ →  CH₄  +  2H₂O

4 moles of hydrogen react to 1 mol of carbon dioxide in order to produce 1 mol of methane and 2 moles of water.

To determine the limiting reactant, we need to know the moles of each reactant.

8.1 g . 1 mol/ 44g = 0.184 moles of carbon dioxide

2.3 g . 1mol / 2g = 1.15 moles of hydrogen

4 moles of hydrogen react to 1 mol of CO₂

Then, 1.15 moles may react to (1.15 . 1) /4 = 0.2875 moles

We only have 0.184 moles of CO₂, so this is the limiting reactant. Not enough CO₂ to complete the 0.2875 moles that are needed.

Ratio is 1:1. 1 mol of CO₂ produces 1 mol of methane

Then, 0.184 moles of CO₂ will produce 0.184 moles of CH₄

We convert moles to mass: 0.184 mol . 16 g /mol = 2.95 g

Describe how nucleic acid basis pair up

Answers

The rules of base pairing (or nucleotide pairing) are: A with T: the purine adenine (A) always pairs with the pyrimidine thymine (T) C with G: the pyrimidine cytosine (C) always pairs with the purine guanine (G)

The nucleotides in a base pair are complementary which means their shape allows them to bond together with hydrogen bonds. The A-T pair forms two hydrogen bonds. The C-G pair forms three. The hydrogen bonding between complementary bases holds the two strands of DNA together.

Please help this is due today! 5-11-2021

Observe the chemical reaction below, and identify if the equation is balanced or not. If it is not balanced, then what coefficient should you place for the reactants and products? Justify with scientific reasoning.

Mg + O2---------> MgO

Make sure to include the following details in your answer in complete sentences:

- Is the chemical reaction balanced?

- Is it following the law of conservation of mass, why is not following?

- What can you do to make sure that the equation becomes balanced and follow the law?

Answers

Answer:

- The chemical reaction is not balanced. There is two oxygens on the reactant's side while there's only one oxygen on the products side.

- I would not say it's following the law of conservation of mass as it's not a balanced equation.

- To balance this equation, you would need to add the coefficient of '2' to Magnesium (Mg) on the reactants side, and add the coefficient of '2' to the products side.  This would make it so that there's 2 Mg's and 2 O's on both the reactant's side and products side.

edit: I hope this helped you in some way. ^^

Which of the gases in air are compounds? Explain how you can tell.

Answers

Answer:

[tex]\huge \underline\bold\red{Answer}[/tex]

The air in the atmosphere consists of nitrogen, oxygen, which is the life-sustaining substance for animals and humans, carbon dioxide, water vapour and small amounts of other elements (argon, neon, etc.). Higher in the atmosphere air also contains ozone, helium and hydrogen.

Answer:

The air in the atmosphere consists of nitrogen, oxygen, which is the life-sustaining substance for animals and humans, carbon dioxide, water vapour and small amounts of other elements (argon, neon, etc.). Higher in the atmosphere air also contains ozone, helium and hydrogen.

On the bottom beam of the triple beam balance, each small division stands for
A.) one centimeter
B.) one milliliter
C.) one gram
D.) one-tenth of a gram

Answers

Answer:

Hello There!!

Explanation:

I believe the answer is D.) one-tenth of a gram.

hope this helps,have a great day!!

~Pinky~

[tex]\huge{\textbf{\textsf{{\color{navy}{An}}{\purple{sw}}{\pink{er}} {\color{pink}{:}}}}}[/tex]

D.) one-tenth of a gram

Thanks.Hope it helps.

A2 Could you remove the iron from the iron sulfide using
magnet?
Explain your answer.

Answers

the iron and sulfur still behave like iron and sulfur in the mixture, but iron sulfide has different properties from both iron and sulfur.

you can separate the iron from the mixture using a magnet, but this does not work for iron sulfide

Find the molality of a solution of 58.5 g NaCl dissolved in 0.556 kg of water

Answers

Answer:lmk

Explanation:

How many moles of O₂ are needed to react completely with 35.0 mol of FeCl₃?


4FeCl3+3O2->2Fe2O3+3Cl2


The 2 for the second half of the equation is not a coefficient it’s supposed to be for 2Fe2 Not 2O3.

26.3 mol

46.7 mol

23.3 mol

10.0 mol

Answers

Answer:

26.3 mol O₂

Explanation:

Step 1: Write the balanced equation

4 FeCl₃ + 3 O₂ ⇒ 2 Fe₂O₃ + 6 Cl₂

Step 2: Establish the appropriate molar ratio

According to the balanced equation, the molar ratio of FeCl₃ to O₂ is 4:3.

Step 3: Calculate how many moles of O₂ are needed to react completely with 35.0 mol of FeCl₃

We will use the previously established molar ratio.

35.0 mol FeCl₃ × 3 mol O₂/4 mol FeCl₃ = 26.3 mol O₂

How many moles is 8.3 x 10^12 atoms or particles of Br2
urgent

Answers

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

[tex]n = \frac{N}{L} \\[/tex]

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

We have

[tex]n = \frac{8.3 \times {10}^{12} }{6.02 \times {10}^{23} } \\ \\ \\ \\ \: \: \: \: \: \: \: = 1.379 \times {10}^{ - 11} \: \: \: \: moles[/tex]

Hope this helps you

How many protons, neutrons, and electrons are found in a neutral atom of hydrogen-333?

Answers

Answer:

Explanation:

A hydrogen atom has an atomic number of 1.

So it's proton number will always be 1.

A neutral hydrogen atom does not have any charge.

So it has the same amount of electrons as protons, which turns out to be also 1.

A neutral hydrogen atom has an atomic mass of ≈

1.00794 amu ≈ 1 amu.

To find the amount of neutrons, we take the proton number and subtract it from the mass number.

1 − 1 = 0

So a neutral hydrogen atom has no neutrons.

In summary,

A hydrogen atom has

1 proton

1 electron

0 neutrons

I hope that helps!

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Solve: Jackson earns $16 per hour. His expenses are $532 per month. Whichexpression shows how much money he has left after his expenses? *532x - 6532x + 1616x - 53216x + 532 i need help plz help me Please help me! DO NOT SEND LINK! Divide X + 3x4x 12 by x +3. Choose any method how did Kennedys foreign policy reflect his view of the world What are two impacts of World War One? No links please:) Name and explain Two Laws/Legislation that protects citizens against Gender-Based Violence..? If a fair coin is tossed 8 times, what is the probability, to the nearest thousandth, of getting exactly 0 tails? Lisa records the number of miles that each of her parents drove each day last week. Her results are shown in the table below.Select ALL the statements about the data that are true. (don't give scam links, please)aThe range of all miles driven by Lisa's father was greater than the range of miles driven by Lisa's mother.bThe average number of miles driven by Lisa's father was greater than the average number of miles driven by Lisa's mother.cThe median number of miles driven by Lisa's father was greater than the median number of mules driven by Lisa's mother.dThe median number of miles driven by Lisa's father was equal to the median number of miles drive by Lisa's mother.eThe average number of miles that Lisa's mother drive Saturday and Sunday was less than the average number of miles that Lisa's father drove on Friday, on Saturday, and on Sunday. 13. Which of the following symbol stands for the margin of error?A. EB. Za/2C.nD.o14. For a 95% confidence level, the confidence coefficient is ___?A. 1.645B. 1.96C.2.33D.2.585.15.What do you call the value resulting from subtracting the margin of error from the sample mean?A. point estimate B. interval estimate C. lower limit of the interval D. upper limit of the intervalFor nos. 16-19A survey on 200 HUMSS students of Bumasa Integrated High School shows that they read on an average of 15. 7 hourper week. The margin of error is 2.2 hours at a 95% confidence level.16. What is the sample mean?A.200B. 95C. 15.7D.2.2 8.17. Which of the following values is the margin of error?A.15.7B. 2.2C. 0.95 D. 0.05 9.D.0.05 9. In the carbon cycle, atmospheric carbon dioxide is converted into organic material by which process? a) transpiration b) cellular respiration c) decomposition d) photosynthesis If there are wastes in our bodies, through homeostasis, our bodies try to get rid of those wastes. What two systems directly remove wastes from the human body? O circulatory & immune immune & nervous excretory & musculoskeletal respiratory & excretory Which of thefollowing could define the function g? Explain your reasoning. Equation A: g(x) = 20 - (1.5)* Equation B: g(x) = 20. (2.5)* Equation C: g(x) = 10. (3.5)* Equation D: g(x) = 20 (4.5)* Karon needs to choose between two gym plans. He can either pay a $150 joining fee and $10 per month, or he can pay a $50 joining fee and $30 per month.PART A: Write a system of equations to model the situation.Gym 1: C = Gym 2: C = PART B: Solve the system to determine on what month the costs of the plans will be equal.The plans will be equal in ___ months and it will cost $___ Equations definitions 2) which of the following is an example of limiting our reliance on fossil fuels ?A- development of hybrid cars B-installing gas powered heating systems in homes C- planting trees D-using coal to fuel trains (please help me with this) i nedd help im almost doneIf yall give me the right answer I called the branly worker to give 1,000 points to right answers so try ya best!!! PromptWhat are some things that your friends did this week? Write 5 complete Spanish sentences describing what they did.Don't forget to conjugate your verbs in the preterite tense! (Use only -er verbs)Pay attention to (a) use of correct preterite form of the verb, (b) appropriate vocabulary usage, and (c) overall quality of eachresponse.Please make it original I dont want her to flag me for coping again. Trench warfare was fought mainly on the eastern front between Germany and Belgium. True False Which of the following represents the graph of the equation y = -2x + 1?