CHEMISTRY HIGH SCHOOL

2MgO à 2Mg + O2 is an example of a _________ chemical reaction.a. synthesis
b. combustion
c. replacement
d. decomposition

Answers

Answer 1
Answer:

Answer:

D. decomposition

Explanation:

Synthesis reaction occurs when two elements or compounds react to originate a new one:

A + B ⇒ C  

Combustion occurs when a fuel reacts with oxygen to form CO₂ and water:

A + O₂ ⇒ CO₂ + H₂O

Replacement reaction can be simple or double. Simple occurs when a simple element replaces others in a compound:

A + BC ⇒ B + AC

Double occurs when two compounds replace elements between them:

AB + CD ⇒ AC + BD

Decomposition reaction occurs when a compound originates two or more compounds

A ⇒ B + C

So, the reaction given is a decomposition chemical reaction.
Answer 2
Answer:

2MgO → 2Mg + O2 is an example of a decomposition chemical reaction. The answer is letter D. It is not a replacement reaction because no other compound is involved. It is not a combustion reaction because no oxygen is involved.

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What is the percent composition by mass of nitrogen in (NH4)2CO3 (gram-formula mass = 96.0 g/mol)? (1) 14.6%
(2) 29.2%
(3) 58.4%
(4) 87.5%

Answers

The percentage composition by mass of nitrogen in {\left( {{\text{N}}{{\text{H}}_{\text{4}}}} \right)_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}} is \boxed{\left( 2 \right){\text{ 29}}{\text{.2 \% }}}.

Further explanation:

The most commonly applied concentration terms are as follows:

1. Molality

2. Mole fraction

3. Molarity

4. Parts per million

5. Mass percent

6. Volume percent

7. Percentage composition

The given compound is {\left( {{\text{N}}{{\text{H}}_{\text{4}}}} \right)_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}. It contains two atoms of nitrogen, eight atoms of hydrogen, one atom of carbon and three atoms of oxygen.

The mass of nitrogen in {\left( {{\text{N}}{{\text{H}}_{\text{4}}}} \right)_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}} can be calculated as follows:

{\text{Mass of N}} =\left( {{\text{Number of nitrogen atoms}}} \right)\left( {{\text{Molar mass of nitrogen}}} \right)              …… (1)

The number of N atoms in {\left( {{\text{N}}{{\text{H}}_{\text{4}}}} \right)_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}} is 2.

The molar mass of nitrogen is 14.01 g/mol.

Substitute these values in equation (1).

 \begin{aligned}{\text{Mass of nitrogen}} &= \left( {\text{2}} \right)\left( {{\text{14}}{\text{.01 g/mol}}} \right)\n&= 28.02{\text{ g/mol}}\n\end{aligned}

The formula to calculate the percentage composition of N in {\left( {{\text{N}}{{\text{H}}_{\text{4}}}} \right)_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}} is as follows:

{\text{\%  composition of N}} = \left( {\frac{{{\text{Mass of N}}}}{{{\text{Mass of }}{{\left( {{\text{N}}{{\text{H}}_{\text{4}}}} \right)}_{\text{2}}}{\text{C}{{\text{O}}_{\text{3}}}}}} \right){\text{100 \% }}                                       …… (2)

The mass of N is 28.02 g/mol.

The mass of {\left( {{\text{N}}{{\text{H}}_{\text{4}}}} \right)_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}} is 96.0 g/mol.

Substitute these values in equation (2).

\begin{aligned}{\text{\%  composition of N}} &= \left( {\frac{{{\text{28}}{\text{.02 g/mol}}}}{{{\text{96}}{\text{.0 g/mol}}}}} \right){\text{100 \% }}\n&= {\text{29}}{\text{.1875 \% }} \n &\approx {\text{2}}{\text{.92 \%}}\n\end{aligned}  

Therefore the percentage composition by mass of nitrogen in {\left( {{\text{N}}{{\text{H}}_{\text{4}}}} \right)_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}} is 29.2 %.

Learn more:

  1. Calculate the moles of chlorine in 8 moles of carbon tetrachloride: brainly.com/question/3064603
  2. What is the concentration of alcohol in terms of molarity? brainly.com/question/9013318  

Answer details:

Grade: Senior School

Chapter: Concentration terms

Subject: Chemistry

Keywords: (NH4)2CO3, N, nitrogen, mass, 2.92 %, 96.0 g/mol, 28.02 g/mol, nitrogen, hydrogen, carbon, oxygen, mass of N, mass of (NH4)2CO3.

The % composition of nitrogen is 29.166% ~ 29.2%. Thus option 2 is correct.

The percent composition of nitrogen in ammonium carbonate can be calculated as:

% Composition = \rm (mass\;of\;element)/(mass\;of\lcompound)\;*\;100

Mass of nitrogen in the compound has been:

Number of Nitrogen atoms = 2

Mass of 1 nitrogen atom = 14 g/mol

Mass of 2 nitrogen atom = 28 g/mol

Mass of compound = 96 g/mol

% Composition of nitrogen = \rm (28)/(96)\;*\;100

% Composition of nitrogen = 29.166 %

The % composition of nitrogen is 29.166% ~ 29.2%. Thus option 2 is correct.

For more information about the percent composition, refer to the link:

brainly.com/question/17505281

What kind of crystal lattice structure is formed when lithium and fluorine combine to form lithium fluoride?

Answers

The lattice structure of Lithium Fluoride (LiF) is comprised of positively charged lithium ions (Li+) and negatively charged fluoride ions (F-) that a linked together by ionic bonds.

The crystal structure of LiF corresponds to that of a face centered cubic (FCC) lattice with Li+ and F- ions occupying the lattice points in the unit cell.

Answer:

Explanation:

An ionic bond is produced between metallic and non-metallic atoms, where electrons are completely transferred from one atom to another. During this process, one atom loses electrons and another one gains them, forming ions. Usually, the metal gives up its electrons forming a cation to the nonmetal element, which forms an anion.

Lithium fluoride is a chemical compound formed through a chemical bond of formula LiF. The electronic configuration of Li is 1s12s1 and that of fluorine is 1s12s22p5. When these atoms come into contact, the 2s1 valence electron of the lithium is transferred to the F atom.

Ionic solids can crystallize in various types of networks, depending on the size of the ions that form it and the charge they possess.

The solid NaCl has a crystalline structure, in which each Na + ion is surrounded by six chloride ions in an octahedral geometry. Therefore, it has a coordination (6: 6) whose numbers indicate how many neighbors surround each ion. The number on the right indicates the neighbors of Na +, while the one on the left, those of Cl–. The structure is based on a compact cubic packing (centered on the faces) of the anions and in which the cations occupy all the octahedral holes. The structure can also be seen as a compact cation packing structure with the anions occupying the octahedral holes. In each unit cell ions of one type occupy the vertices and centers of the faces of the cube while those of the opposite sign are located in the centers of the edges and in the center of the cube.

Suggest two reasons why the UK government wants to encourage recycling of iron and steel......

Answers

The two reasons why the UK government is encouraging citizens to recycle iron and steel is:
1.   The environment. Every machinery and device the industries makes which includes, infrastructures, mega structures to micro devices. Iron and steel is used. Reducing the extraction of ore and creating steel saves the environment, reduces mining.
2.   Economic reasons. When the ore mining and steel making is reduced in activity, the government won’t just be able to save the environment but it also save funds for other purposes.



Calculate the density of argon gas at a pressure of 753 mmHg and a temperature of 35 °C

Answers

The density of Argon gas at a pressure of 753 mmHg and a temperature of 35 °C is equal to 1.59 g/L.

What is the ideal gas equation?

The state of a quantity of gas is calculated by its pressure, volume, and temperature. The ideal gas law can be explained as the product of the volume and pressure of gas is equal to the multiplication of the universal gas constant and absolute temperature.

The mathematical equation for an ideal gas can be written as follows:

PV = nRT

PV =(m/M) RT

PM/RT = m/V

d = PM/RT

Where n is the moles of gas, T is the temperature of the gas,  V is the volume of the gas,  and R is the gas constant.

Given, the temperature of argon gas, T = 35 °C = 35 +273 = 308 K

The pressure of the argon gas, P = 753 mmHg = 1.01 atm

The molar mass of the Argon gas, M = 40 g/mol

Substitute  V, R, P, and T in the ideal gas equation, we get:

The density of Argon gas, d = PM/RT

d= 1.01 ×40/(0.082 × 308)

d = 1.59 g/L

Therefore, the density of Ar gas is 1.59 g/L.

Learn more about ideal gas equation, here:

brainly.com/question/3637553

#SPJ2
PV=nRT
PV= (m/M)RT
PM=(m/v)RT
PM =dRT
d= (PM) ÷(RT)

substitute the the given data to the above equation. d-density, p-pressure, M- molar mass of argon gas, T- temperature. and R is a constant. make sure to substitute its value too.. :)

What is not part of the cell theory except organism

Answers