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3 years ago

Which phase change is exothermic?

Chemistry

2 answers:

Black_prince [1.1K]3 years ago

8 0

C. Melting ! pls lmk if that was correct !:)

vova2212 [387]3 years ago

7 0

Answer:

B. Solidification

Hope this helped! :)

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PLEASE HELP ME ASAP Identify the arrows that show the correct direction of heat transfer.

adell [148]

Answer: Left Arrow Far right arrow and center left arrow

Explanation:

These three arrows are correct due to heat transfers to cooler temp environments which allows the expansion of speed for molecules in their environment.

6 0

4 years ago

Ii) During burning, elements in the coal are converted to compounds called ????

elena-s [515]

Answer:

Gasification refers to the conversion of coal to a mixture of gases, including carbon monoxide, hydrogen, methane, and other hydrocarbons, depending on the conditions involved.

6 0

3 years ago

In Experiment 9, a 1.05 g sample of a mixture of NaCl (MW 58.45) and NaNO2 (MW 69.01) is reacted with excess sulfamic acid. The

Kaylis [27]

Answer:

There is 76.6 mL of nitrogen collected

Explanation:

Step 1: Data given

Mass of the sample = 1. 05 grams

The sample is 40.00% by mass NaNO2

MW of NaCl = 58.45 g/mol

MW of NaNO2 = 69.01 g/mol

Temperature = 22.0 °C

Pressure = 750.0 mmHg = (750/760) atm

The vapor pressure of water at 22.0°C is 19.8 mm Hg = 0.02605 atm

Step 2: Calculate mass of NaNO2

(40/100)*1.05 = 0.42 grams

Step 3: Calculate moles of NaNO2

Moles NaNO2 = 0.42 grams / 69.01 g/mol

Moles NaNO2 = 0.00608 moles

Step 4: Calculate moles of N2

For 2 moles of NaNO2 we'll get 1 mol of N2

For 0.00608 moles of NaNO2 we'll get 0.00608/2 = 0.00304 moles

Step 5: Calculate pressure of N2

P = 750.0 - 19.8 = 730.2 mmHg = (730.2/760)atm = 0.96079 atm = 97352 Pa

Step 6: Calculate volume of N2

PV = nRT

⇒ P = the pressure of N2 = 0.96079

⇒ V = the volume of N2 = TO BE DETERMINED

⇒ n = moles of N2 = 0.00304 moles

⇒ R = the gas constant = 0.08206 L*atm/K*mol

⇒ T = the temperature = 22°C = 295 Kelvin

V = (0.00304*0.08206*295)/0.96079

V = 0.0766 L = 76.6 mL

There is 76.6 mL of nitrogen collected

4 0

4 years ago

Elements within the same group of the periodic table behave similarly because they have the same number of ?

sammy [17]

The elements in each group have the same number of electrons in the outer orbital. Or also called valence electrons. Khan academy has a great video online explaining why this happens. (It only happens for main group elements). Here is a link (sorry you can’t click it in Brainly) https://www.khanacademy.org/science/chemistry/periodic-table/copy-of-periodic-table-of-elements/v/periodic-table-valence-electrons. Feel free to message me for a better explanation, I would explain now but I’m not sure how much you know about this. If you know how to write an electron configuration you can see how all the electron configurations for the same group (not the transitional metals only the main groups) have the same number of valence electrons. I hope that helped, sorry I was vague about the explanation :)

4 0

3 years ago

Hello! Id like if someone could tell me this answer, thank you so much!

DaniilM [7]

Answer:

Option D. ZnCl₂ and H₂

Explanation:

From the question given above, the following equation was obtained:

2HCl + Zn —> ZnCl₂ + H₂

Products =?

In a chemical equation, reactants are located on the left side while products are located on the right side i.e

Reactants —> Products

Now, considering the equation from the question i.e

2HCl + Zn —> ZnCl₂ + H₂

The products are ZnCl₂ and H₂ because from our discussion above, we said that products are only located on the right side of chemical equation.

Thus, option D gives the correct answer to the question.

4 0

3 years ago