Which of the following is not a pure form of a substance ?

A.Element
B.Atom
C.Molecule
D.Mixture
E.Compound

When heating up, the balloon slowly rises and flies up in the air again. Explanation: The volume of the balloon decreases by the low temperature, because the gas inside is cooled down. When heated up, the pressure in the balloon rises, the balloon expands, and will reach to its original shape.

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Answer:

SnO2(aq) + 2H2(g) → Sn(s) + 2H2O(g) - Redox reaction

AgNO3(aq) + KI(aq) → AgI(s) + KNO3(aq) - double replacement reaction

2Fe(s) + 3Br2(l) → 2FeBr3(s) - Formation

3H2SO4(aq) + 2Fe(s) → Fe2(SO4)3(aq) + 3H2(g) - Single replacement

2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(g) - Hydrocarbon combustion

4Al(s) + 3O2(g) → 2Al2O3(s) - Formation

2KI(l) → 2K(s) + I2(s) - Decomposition

3CaCl2(aq) + 2Na3PO4(aq) → Ca3(PO4)2(s) + 6NaCl(aq) - Double replacement

Explanation:

In an oxidation - reduction reaction, the oxidation number of the species involved in the reaction changes from left to right. One specie is oxidized while the other is reduced. E.g in SnO2(aq) + 2H2(g) → Sn(s) + 2H2O(g) - Sn^2+ was reduced while H2 was oxidized.

For a single replacement reaction, one specie is replaced in the reaction e.g H^+ is replaced by Fe^2+ in the reaction, 3H2SO4(aq) + 2Fe(s) → Fe2(SO4)3(aq) + 3H2(g) .

In a double replacement reaction, the ions on the reactant side exchange partners at the product side e.g 3CaCl2(aq) + 2Na3PO4(aq) → Ca3(PO4)2(s) + 6NaCl(aq)

In a formation reaction, two reactants combine to form a product. E.g 2Fe(s) + 3Br2(l) → 2FeBr3(s)

In a decomposition reaction, a compound breaks down to yield its components e.g 2KI(l) → 2K(s) + I2(s)

Hydrocarbon combustion refers to the reaction of a hydrocarbon compound with oxygen e.g 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(g)

Answer:

1.89 × 10^-11 M

Explanation:

Recall that;

[H^+] [OH^-] = 1 × 10^-14

[H^+] = concentration of hydronium ions

[OH^-] = concentration of hydroxide ion

Where [OH^-] = 5.3 × 10−4 M

[H^+]= 1 × 10^-14/5.3 × 10−4

[H^+]= 1.89 × 10^-11 M

Milk of magnesia, with a concentration of hydroxide ions of 5.3 × 10⁻⁴ M, has a concentration of hydronium ions of 1.9 × 10⁻¹¹ M.

Milk of magnesia (Mg(OH)₂) is an antacid, in which the concentration of hydroxide ions is 5.3 × 10⁻⁴ M.

We can calculate the concentration of hydronium ions at 25°C using the following expression.

[tex][H_3O^{+} ][OH^{-} ] = Kw = 1.0 \times 10^{-14} \\\\[H_3O^{+} ] = \frac{1.0 \times 10^{-14} }{[OH^{-} ]} = \frac{1.0 \times 10^{-14} }{5.3 \times 10^{-4} } = 1.9 \times 10^{-11} M[/tex]

where,

Since [H₃O⁺] < 10⁻⁷ M, the milk of magnesia is basic.

Milk of magnesia, with a concentration of hydroxide ions of 5.3 × 10⁻⁴ M, has a concentration of hydronium ions of 1.9 × 10⁻¹¹ M.

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Answer:

yes it does

Explanation:

because the ratios on the reactants and products are equal

The reaction 2Na(s) + Cl₂(g) → 2NaCl(s) obeys the law of conservation of mass.

Yes, this reaction obeys the law of conservation of mass. The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction; it is only rearranged.

In the given reaction, we have 2 sodium atoms (Na) on the left side and 2 sodium atoms (Na) on the right side. Similarly, we have 2 chlorine molecules (Cl₂) on the left side and 2 chlorine atoms (Cl) on the right side. Therefore, the number of atoms of each element is balanced on both sides of the reaction.

Additionally, the total mass of the reactants (2Na + Cl₂) is equal to the total mass of the product (2NaCl). The coefficients in the balanced equation represent the stoichiometric ratios, ensuring that the mass is conserved.

Hence, the reaction 2Na(s) + Cl₂(g) → 2NaCl(s) obeys the law of conservation of mass.

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Answer: the atomic size will decrease

Explanation:

Answer:

It will remain the same because it is moving up and down to and fro it can not increase nor decrease or else will become an ion

Answer:

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Explanation:

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Answer:

½N 2(g) + O 2(g) + 8.1 kcal → NO 2(g)

½N 2(g) + ½O 2(g) → NO(g), ΔH = +21.6 kcal/mole

NH 3(g) → ½N 2(g) + 3/2H 2(g), ΔH = +11.0 kcal/mole

General Formulas and Concepts:

Thermochemistry

Explanation:

An endothermic reaction would have heat or energy gained in the final stage of the reaction.

This means that our enthalpy would be positive and heat/energy would be added as a reactant.

Out of all the answer choices, we see that only these have heat/energy added in the reactant side or the enthalpy being positive:

½N 2(g) + O 2(g) + 8.1 kcal → NO 2(g)

½N 2(g) + ½O 2(g) → NO(g), ΔH = +21.6 kcal/mole

NH 3(g) → ½N 2(g) + 3/2H 2(g), ΔH = +11.0 kcal/mole

Topic: AP Chemistry

Unit: Thermochemistry

Answer:

The number of hydrogen atoms is 4.96x10²⁴.

Explanation:

The number of atoms can be found with the following equation:

[tex] n = N*\eta_{H} [/tex]

Where:

N: is the Avogadro's number = 6.022x10²³ atoms/mol

η: is the number of moles of hydrogen

n: is the number of hydrogen atoms

First, we need to find the number of hydrogen moles. The number of moles of CH₄ is:

[tex] \eta_{CH_{4}} = \frac{m}{M} [/tex]

Where:

m: is the mass of methane = 33 g

M: is the molar mass of methane = 16.04 g/mol                      

[tex] \eta_{CH_{4}} = \frac{33 g}{16.04 g/mol} = 2.06 mol [/tex]

Now, since we have 4 hydrogen atoms in 1 mol of methane, the number of moles of hydrogen is:

[tex] \eta_{H} = 2.06\: mol\: CH_{4}*4 \frac{mol\: H}{mol \: CH_{4}} = 8.24 mol [/tex]

Hence, the number of hydrogen atoms is:

[tex]n = N*\eta_{H} = 6.022 \cdot 10^{23} \: atoms/mol*8.24 mol = 4.96 \cdot 10^{24} atoms[/tex]

Therefore, the number of hydrogen atoms is 4.96x10²⁴.

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Answer:

propene and hydrogen is product

When propanol is heated with concentrated sulphuric acid at 443 K, dehydration takes place and prop-1-ene is formed. In this reaction concentrated sulphuric acid acts as a dehydrating agent.

I. A + HCl gives )-gives 2-chloropropane

II. A --> Combustion ( what product does it form. Write out the equation propene ozonide

III.A ---> Hydrogenation (what product does it form. Write out the equation )propanol

None

Explanation:

methylene is an organic compound comprising and of One carbon and two hydrogens

Answer: The answer is they are not closely packed

Explanation: HOPE THIS HELPS!!

Answer:

Can you translate for me please

the 1st one is balanced, the 2nd isn't (the number of Mg differs from left 1 to right 2).

The third is also not balanced, 2 F left,2*3=6 on the right

Answer:

It's a double displacement reaction.

The answer is ‘Passive Transport’

movement of molecules without the use of energy is due to the shrinkage of water

Answer:

carbon reaction with iron from its oxide. Why?? Because it is largely used in extraction of metals. It is used in acid indigestion.

Answer:

CO32-(aq) + 2H+(aq) → CO2(g) + H2O(l)

Explanation:

According to this question, sodium carbonate reacts with sulfuric acid to form aqueous sodium sulfate, carbon dioxide and water. The balanced chemical equation is as follows:

Na2CO3(aq) + H2SO4(aq) → Na2SO4(aq) + CO2(g) + H2O(l)

- Next, split compounds that are aqueous into ions.

2Na+(aq) + CO32-(aq) + 2H+(aq) + SO42-(aq) → 2Na+(aq) + SO42-(aq) + CO2(g) + H2O(l)

- Next, we cancel out the spectator ions, which are ions that remain the same in the reactants and products side of a chemical reaction. The spectator ions in this equation are 2Na+(aq) and SO42-(aq).

CO32-(aq) + 2H+(aq) → CO2(g) + H2O(l)

- Hence, the balanced ionic equation is as follows:

CO32-(aq) + 2H+(aq) → CO2(g) + H2O(l)

Answer: It’s 4.0

Explanation: I just took the test and got it right:)

Answer:

I think option (d) is right answer

Answer:

I think that the answer is option(C)

Answer:

I would guess more atoms? but there is no graph attached

An air mass is a volume of air whose temperature and humidity are specified. Many hundreds or thousands of square miles are covered by air masses, which adjust to the properties of the land underneath them.

An air mass is a volume of air whose temperature and humidity are specified. Many hundreds or thousands of square miles are covered by air masses, which adjust to the properties of the land underneath them. Latitude and their continental or marine source regions are used to categorize them.

There is a temperature and air pressure differential. Storms are caused by abrupt changes in the weather. Two natural wind patterns come into conflict.

The hot and dry continental tropical (cT) air mass is prevalent over subtropical and tropical continents. The world's largest deserts, such the Sahara, Arabian, and Australian, are important source areas.

Thus, Latitude and their continental or marine source regions are used to categorize them. An air mass is a volume of air whose temperature and humidity are specified.

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Answer:

the atomicity of sulphur is 8

Explanation:

hope it helps

Answer:

A. 70 K

B. 3.16 atm

Explanation:

We'll begin by calculating the number of mole in 175 g of Ar. This can be obtained as follow:

Mass of Ar = 175 g

Molar mass of Ar = 40 g/mol

Mole of Ar =?

Mole = mass / molar mass

Mole of Ar = 175 / 40

Mole of Ar = 4.375 moles

A. Determination of the temperature.

Mole of Ar (n) = 4.375 moles

Volume (V) = 2.50 L

Pressure (P) = 10 atm

Gas constant (R) = 0.0821 atm.L/Kmol

Temperature (T) =?

PV = nRT

10 × 2.5 = 4.375 × 0.0821 × T

25 = 4.375 × 0.0821 × T

Divide both side by (4.375 × 0.0821)

T = 25 / (4.375 × 0.0821)

T ≈ 70 K

B. Determination of the pressure.

Mole of Ar (n) = 4.375 moles

Volume (V) = 2.50 L

Temperature (T) = 22 K

Gas constant (R) = 0.0821 atm.L/Kmol

Pressure (P) =?

PV = nRT

P × 2.5 = 4.375 × 0.0821 × 22

Divide both side by 2.5

P = (4.375 × 0.0821 × 22) / 2.5

P = 3.16 atm.

Answer:

D

Explanation:

B is solid and liquid while D is liquid and gas

Answer:

Option ( D) is correct

The phase transition occurs at 100o C (the normal boiling point of water). Liquid water becomes water vapor or steam when it enters the gaseous phase.

Explanation:

A heating curve graphically represents the phase transitions that a substance undergoes as heat is added to it.

The liquid will begin to boil when enough heat has been absorbed by the solution that the temperature reaches the boiling point, where again, the temperature remains constant until all of the liquid has become gaseous water. At the atmospheric pressure of 1 atm, this phase transition occurs at 100o C (the normal boiling point of water). Liquid water becomes water vapor or steam when it enters the gaseous phase. Use the heat of vaporization ([latex]\Delta H_{vap}[/latex] ) to calculate how much heat was absorbed in this process: [latex]q=m\cdot C_{H_2O(g)}\cdot \Delta T[/latex], where m is the mass of the sample of water.

After all of the liquid has been converted to gas, the temperature will continue to increase as heat as added. Again, the heat added that results in a certain change temperature is given by: [latex]q=m\cdot C_{H_2O(g)}\cdot \Delta T[/latex] . Note that the specific heat capacity of gaseous water is different than that of ice or liquid water.

Answer:

This is because Mendeleev arranged the elements in order of increasing relative atomic mass.

Explanation:

Dmitri Mendeleev is one of the scientists that contributed to the development of periodic table in chemistry. He was able to organise elements into rows according to their atomic mass and into columns based on chemical and physical properties. This is the main reason why his periodic table is still studied even though it has some defects which include:

--> Grouping of elements that are not similar chemically: For example Copper and Silver bear no resemblance with the alkali metals, but they have been placed together in the first group.

--> Position of isotopes: According to his periodic table: Isotopes of an element must be given separate places in the periodic table because they have different atomic masses.

--> Electronic arrangement of elements: It failed to explain the electronic arrangement of elements.

--> Separation of chemically similar elements:

Elements that are chemically similar such as Gold and Platinum have been placed in separate groups.

Answer:

[tex]\boxed {\boxed {\sf 761 \ K}}[/tex]

Explanation:

We are asked to find the new temperature of a gas after a change in volume. We will use Charles's Law, which states the volume of a gas is directly proportional to the temperature. The formula for this law is:

[tex]\frac {V_1}{T_1}= \frac{V_2}{T_2}[/tex]

The volume is initially 52.3 liters at a temperature of 273 Kelvin.

[tex]\frac {52.3 \ L}{273 \ K}= \frac{V_2}{T_2}[/tex]

The volume reaches 145.7 liters at an unknown temperature.

[tex]\frac {52.3 \ L}{273 \ K}= \frac{145.7 \ L }{T_2}[/tex]

We are solving for the new temperature, so we must isolate the variable T₂.  Cross multiply. Multiply the first numerator and second denominator, then the first denominator and second numerator.

[tex]52.3 \ L * T_2 = 273 \ K * 145.7 \ L[/tex]

Now the variable is being multiplied by 52.3 liters. The inverse of multiplication is division. Divide both sides by 52.3 L.

[tex]\frac {52.3 \ L * T_2 }{52.3 \ L}=\frac{ 273 \ K * 145.7 \ L}{52.3 \ L}[/tex]

[tex]T_2=\frac{ 273 \ K * 145.7 \ L}{52.3 \ L}[/tex]

The units of liters cancel.

[tex]T_2=\frac{ 273 \ K * 145.7 }{52.3 }[/tex]

[tex]T_2 = 760.5372849 \ K[/tex]

The original measurements have at least 3 significant figures, so our answer must have 3. For the number we found, that is the ones place. The 5 in the tenths place tells us to round the 0 up to a 1.

[tex]T_2 \approx 761 \ K[/tex]

When the volume reaches 145.7 liters, the temperature is 761 Kelvin.

Answer:

NAO SRESONDEPORR PQUEOU BUOBRRRA  IGAD THCAAUSEI

Explanation: