Which compound is formed from its elements by an exothermic reaction at 298 K and 101.3 kPa?

Answers

Answer 1

Answer:

STP means standard temperature and pressure at 0°C (273K) and 1 atm (atmosphere). The density of the unknown gas is 0.63 gram per liter. The deal gas equation is PV = nRT. The n is the numer of moles and can be represented as mass of the gas, m, divided by the molar mass, c. so we have,

PV = nRT

PV = (m/c)RT

Since the density is d = m/V

Pc = (m/V)RT

Pc = dRT

c = drT/P

substitute the values into the equation,

c = [(0.63g/L)(0.08206 L-atm/mol-K)(273K)]/(1atm)

c = 14.11 g/mol

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A sample contains 6.25 percent parent isotope and 93.75 percent daughter isotopes. If the half-life of the parent isotope is 58 years, how old is the sample?

Answers

The parent isotope percent will change from 100% to 50% to 25% to 12.5% and to 6.25%. So the sample go through four times of half-life. So the sample is 58*4=232 years old.

Answer is: the sample is 232 years old.

Take 100 atoms:

After first half-life: 50% · 100 ÷ 100% = 50.

After second half-life: 0.5 · 50 = 25.

After third half-life: 0.5 · 25 = 12.5.

After fourth half-life: 0.5 · 12.5 = 6.25.

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Which of the following statements are correct about the chemical reaction?H2 + O2 -> H2O2
versus
2 H2 + O2 -> 2 H2O?
They are both balanced chemical equations.
The two reactions are equivalent.
The laws of thermodynamics apply to both.
Conservation of mass applies to both.

Answers

The correct answer for the question that is being presented above is this one: "They are both balanced chemical equations." The statement that is correct about the chemical reaction is that both chemical reaction are balanced chemical equations.

Why does hybridization of orbitals occur?

Answers

Hybridization of orbitals is the concept of incorporation atomic orbitals into new hybrid orbitals appropriate for the pairing of electrons to form chemical bonds in valence bond theory.

In the electron cloud model, if you begin at the electron shell closest to the nucleus of an atom and move out, what is the number of electrons that each energy level or electron shell needs to fill the first four electron shells?A. 2, 6, 10, 14
B. 2, 8, 18, 32
C. 8, 8, 8, 8

Answers

Option B: 2, 8, 18, 32.

2 in the K shell, 8 in L shell, 18 in M shell and 32 in N shell.

What is the balanced equation of Ca3(PO4)2+ SiO+ C---> P+ CaSiO+ CO

Answers

Balanced chemical equation:

1 Ca3(PO4)2 + 3 SiO2 + 11 C = 2 P + 3 CaSiO + 11 CO

hope this helps!.

A chemical with a bitter taste is most likely a(n) _____ a. salt.
b. solvent.
c. acid.
d. base.

Answers

(D)Base has a bitter taste

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