What sign of chemical change occurs during chemiluminesence?Production of heat
Production of a gas
Production of light
O Production of a solid (precipitation)

Answers

Answer 1
Answer:

Answer:

Emission of Light

Explanation:

Chemiluminescence is the emission of light as the result of a chemical reaction, and not a property of a specific compound.

Dont know if you were asking for this but hope it helps


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PLEASE HELP IMMEDIATELY ​

QUICK WILL MARK BRAINLIEST!!Match each of the unknown ions to its appropriate description.

A− A) A nonmetal that gained one electron
B+ B) A metal that lost one electron
C2− C) A metal that lost two electrons
D2+ D) A nonmetal that gained two electrons

Answers

Answer:

c2-c

Explanation:

A mental that lost two electrons just joking I don't k ow but I think it ain't the first o e because of comment sense to the 5th power

Answer:

A and B

Explanation:

metal form ion by lossing elecron

non metal form ion by gaining electron

It is the outermost layer of the solid portion of earth

Answers

Answer:

Crust.

Explanation:

Its is made up hard rocks

Answer:lithosphere

The lithosphere is the solid, outer part of the Earth. The lithosphere includes the brittle upper portion of the mantle and the crust, the outermost layers of Earth's structure.

Explanation:

Which is the most stable? Carbon (C) Sodium (Na) Helium (He)

Answers

the answer is helium because

The enthalpy of combustion of acetylene C2H2 is described by C2H2(g) + (5/2) O2(g) →2CO2(g) + H2O(l), Hrxn= –1299 kJ/mol. Calculate the enthalpy of formation of acetylene, given the following enthalpies of formation Hf[CO2(g)] = –393.5 kJ/mol Hf[H2O(l)] = –285.8 kJ/mo

Answers

Answer:

226.2 kJ/mol

Explanation:

Let's consider the following thermochemical equation for the combustion of acetylene.

C₂H₂(g) + (5/2) O₂(g) → 2 CO₂(g) + H₂O(l), ΔH°rxn = –1299 kJ/mol.

We can also calculate the enthalpy of the reaction per mole of acetylene from the enthalpies of formation.

ΔH°rxn = 2 mol × ΔH°f(CO₂(g)) + 1 mol × ΔH°f(H₂O(l)) - 1 mol × ΔH°f(C₂H₂(g)) - 1 mol × ΔH°f(O₂(g))

1 mol × ΔH°f(C₂H₂(g)) = 2 mol × ΔH°f(CO₂(g)) + 1 mol × ΔH°f(H₂O(l)) - ΔH°rxn - 1 mol × ΔH°f(O₂(g))

1 mol × ΔH°f(C₂H₂(g)) = 2 mol × (-393.5 kJ/mol) + 1 mol × (-285.8 kJ/mol) - (-1299 kJ) - 1 mol × (0 kJ/mol)

ΔH°f(C₂H₂(g)) = 226.2 kJ/mol

Answer:

The enthalpy of formation of acetylene is 226.2 kJ/mol

Explanation:

Step 1: Data given

C2H2 (g) + (5/2)O2 (g)  → 2CO2 (g) + H2O (l)  Heat of Reaction (Rxn) = -1299kJ/mol

Standard formation [CO2 (g)]= -393.5 kJ/mol

Standard formation [H2O (l)] = -285.8 kj/mol

Step 2: The balanced equation

The formation of acetylene is:

2C(s) + H2(g)   → C2H2(g)

Step 3: Calculate the enthalpy of formation of acetylene

It doesn't matter if the process will happen in 1 step or in more steps. What matters is the final result. This is Hess' law of heat summation.

To have the reaction of the formation of acetylene we have to take:

⇒ the reverse equation of the combustion of acetylene

   2CO2 (g) + H2O (l) → C2H2 (g) + (5/2)O2 (g)

⇒  The equation of formation of CO2 (multiplied by 2)

2C(s) + 2O2(g) → 2CO2(g)

⇒ the equation of formation of H2O

H2(g) + 1/2 O2(g) → H2O(l)

2CO2 (g) + H2O (l) + 2C(s) + 2O2(g) + H2(g) + 1/2 O2(g  → C2H2 (g) + (5/2)O2 (g) + 2CO2(g) + H2O(l)

Final reaction = 2C(s) + H2(g)   → C2H2(g)

Calculate the enthalpy of formation of acetylene =

ΔHf = 1299 kJ/mol + (2*-393.5) kJ/mol + (-285.8) kJ/mol

ΔHf = 226.2 kJ/mol

The enthalpy of formation of acetylene is 226.2 kJ/mol

Which of the following equations violates the law of conservation of mass? A. FeCl3 + 3NaOH yields Fe(OH)3 + 3NaCl

B. CS2 + 3O2 yields CO2 + 2SO2

C. Mg(ClO3)2 yields MgCl2 + 2O2

D. Zn + H2SO4 yields H2 + ZnSO4

Answers

Hi!

The chemical equation that violates the law of conservation of mass is C

Mg(ClO₃)₂ → MgCl₂ + 2O₂

Let's see why:

The number of atoms from each element should be the same on both sides of the equation.

For Mg:
1 atoms Left Side=1 atoms Right Side
For Cl:
2 atoms Left Side=2 atoms Right Side
For O: 6 atoms Left Side ≠ 4 atoms Right Side

So, the equation is not balanced for O. 
The correct balanced equation is the following:

Mg(ClO₃)₂ → MgCl₂ + 3O₂

Have a nice day!

A mixture contains N a H C O 3 together with unreactive components. A 1.68 g sample of the mixture reacts with H A to produce 0.561 g of C O 2 . What is the percent by mass of N a H C O 3 in the original mixture

Answers

There is 65% of NaHCO3 in the sample.

The equation of the reaction is;

HA + NaHCO3 -----> NaA + CO2 + H2O

Amount of CO2 formed = mass/molar mass

mass of CO2 = 0.561 g/44 g/mol = 0.013 moles

From the balanced reaction equation;

1 mole of NaHCO3 yields 1 mole of CO2

0.013 moles of Na2CO3 yields 0.013 moles of CO2

Hence, mass of NaHCO3 in the sample = 0.013 moles × 84 g/mol = 1.092 g of NaHCO3

Percentage by mass of NaHCO3 = 1.092 g/1.68 g ×100/1

= 65%

Learn more: brainly.com/question/25150590

Answer:

63.75%.

Explanation:

The first step here is to write out the reaction showing the chemical reaction between the two chemical species. Thus, we have;

HA(aq) + NaHCO3 --------------> CO2(g) + H20(l) + NaA(aq).

Therefore, the mole ratio is 1 : 1 : 1 : 1 that is go say one mole of HA reacted with one mole of NaHCO3 to give one mole of CO2 and one .ole of NaA.

Hence, the number of moles of CO2 = mass/molar mass = 0.561/44 = 0.01275 moles.

Thus, the number of moles of NaHCO3 = number of moles of CO2 = 0.01275 moles.

Therefore, we have ( 0.01275 moles × 84 g/mol) grams = 1.071 g NaHCO3 in the mixture.

Therefore, the percent by mass of N a H C O 3 in the original mixture = 1.071/1.68 × 100 = 63.75%.