7.71 Classify each of the following as exothermic or endothermic:
a. CHÂ(g) + 2O₂(g) —^> CO₂(g) + 2H₂O(g) + 802 kJ
b. Ca(OH)₂(s) + 65.3 kJ →→→ CaO(s) + H₂O(l)
c. 2Al(s) + Fe₂O3(s) — Al₂O3(s) + 2Fe(s) + 850 kJ

Empirical formula of the Cyclopropane = C[tex]H_{2}[/tex]

Molecular formula  of the Cyclopropane = [tex]C_{3} H_{6}[/tex]

Cyclopropane is a cyclic compound having 3 carbon atoms in a ring.

As we know carbon is having 4 valency, that means it can form 4 bonds with other atoms.

In case of cyclopropane each carbon atom is attached with 2 carbon atoms in a ring, so 2 valency of each carbon atom is used in a ring formation.

The remaining 2 valency are satisfied by hydrogen atoms.

Here, 3 carbons are there so 6 hydrogens are used to satisfy their valency.

An empirical formula is a simple representation of ratio of the atoms present, while a molecular formula is a detailed representation of the total number of atom.

So here, carbon and hydrogen ratio is 1:2 , from this the Empirical formula of the Cyclopropane became C[tex]H_{2}[/tex]

And the molecular formula of  the Cyclopropane is [tex]C_{3} H_{6}[/tex].

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Answer:

c

Explanation:

because heat is taken in in sublimation.

Sublimation is the straight transition from a solid state of materials to a vapor state upon heating (without becoming liquid). The row about a change of state which is correct is C.

Sublimation is the transition of a substance from its solid to its gaseous state without passing through a liquid phase. Sublimation is the term most frequently used to describe the process by which snow and ice turn into water vapor (gas) in the atmosphere without first melting into a liquid for those of us who are interested in the water cycle.

The best illustration of sublimation is dry ice, which is carbon dioxide that has been frozen. Dry ice directly transforms from its solid state to a gaseous state, which is visible as fog, when it is exposed to air. The gaseous state of frozen carbon dioxide is more stable than the solid state.

Thus the correct option is C.

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Answer:

B) As you move across the row, the number of electrons increases and reactivity also increases.

Explanation:

The periodic table is arranged in a way that if you go across a period, the number of protons, neutrons, and electrons in an element increases. In terms of reactivity, the most reactive elements are the ones which have a high electronegativity. The electronegativity of the elements increases as you travel to the right and upwards on the periodic table.

The equation for the overall reaction obtained by adding these equations is;  2NO₂(g) ⇒ N₂O₄(g)

We are given equations;

2NO₂(g) ----> 2NO(g) + O₂(g)   ---(1)

2NO(g) -----> N₂(g) + O₂(g)   -----(2)

N₂(g) + 2O₂(g) ----> N₂O₄(g)   -----(3)

Add eq 1 and eq 2 to get;

2NO₂(g) + 2NO(g) ⇒ 2NO(g) + O₂(g) + N₂(g) + O₂(g)

2NO will cancel out to get;

2NO₂(g) ⇒ N₂(g) + 2O₂(g)   -----(4)

Add eq 3 to eq 4 to get;

N₂(g) + 2O₂(g) + 2NO₂(g) ⇒ N₂O₄(g) + N₂(g) + 2O₂(g)

This will reduce to;

2NO₂(g) ⇒ N₂O₄(g)

The correct question is;

Consider the chemical equations shown here.

2NO₂(g) ----> 2NO(g) + O₂(g)

2NO(g) -----> N₂(g) + O₂(g)

N₂(g) + 2O(g) ----> N₂O₄(g)

What is the equation for the overall reaction obtained by adding these equations?

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Answer:

A &D

Explanation:

I took it

Answer:

Both metals and non-metals when burnt in oxygen form their oxides. Oxides of metals are basic in nature and oxides of non-metals are acidic in nature.

Answer:

Tablets are made from salts of iron hence it does not look like iron.

Explanation:

Answer:

last choice

Explanation:

Specific heat of a metal is    j/kg-c

It says nothing about melting point or heat of fusion

A = twice B   =  2 * j/kg-c       B = j/kg-c

 if   j is constant and mass is the same we can write this more like

    A = 2 /C       and    B = 1/C

  or    A ~  C/2      and   B~  C

now you can see that the temp change in A   will be 1/2   that of B

The complete table is inserted.

A table is given,

Formulas used:

pH=  -log(H⁺)

pOH=  -log(OH⁻)

pH+ pOH=14

Calculations:

For A: (H⁺)=2×10⁻⁸M

Using the pH formula:

pH=  -log(H⁺)=-log(2×10⁻⁸)=7.69

pOH=14 - 7.69=6.3

Calculating OH concentration,

pOH=  -log(OH⁻)

6.3= -log(OH⁻)

(OH⁻)=5.011×10⁻⁷M

Hence, the nature of A is basic.

Similarily,

For B,

(OH⁻)=1×10⁻⁷

Using the pH formula:

pOH=  -log(OH⁻)= -log(1×10⁻⁷)=7

pH=14-7=7

Calculating H concentration,

pH=  -log(H⁺)

7= -log(H⁺)

(H⁺)=1×10⁻⁷M

Hence, the nature of B is neutral.

Similarily,

For C,

pH=12.3

Using the pH formula:

pOH=14-12.3=1.7

Calculating H concentration,

pH=  -log(H⁺)

12.3= -log(H⁺)

(H⁺)=5.011×10⁻¹³M

Calculating OH concentration,

pOH=  -log(OH⁻)

1.7= -log(OH⁻)

(OH⁻)=1.99×10⁻²M

Hence, the nature of C is Basic.

Similarily,

For D,

pOH=6.8

Using the pH formula:

pH=14-6.8=7.2

Calculating H concentration,

pH=  -log(H⁺)

7.2= -log(H⁺)

(H⁺)=6.309×10⁻⁸M

Calculating OH concentration,

pOH=  -log(OH⁻)

6.8= -log(OH⁻)

(OH⁻)=1.58×10⁻⁷M

Hence, the nature of D is basic.

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The number of moles of gas, a balloon inflated to 7 L of volume at STP will be 0.31 moles.

The molar volume of a gas is the volume of one mole of a gas at STP.

At STP, one mole (6.02×10²³ particles) of any gas occupies a volume of 22.4 L

Therefore,

If 1 mole of any gas occupies 22.4 L of volume at STP

Then, X mole of gas occupies 7 L of Volume at STP

Now,

Let's equate both the above conditions ;

X / 7 L = 1 / 22.4 L

  X      = 1/ 22.4 L x 7 L  

  X      = 0.31 moles

Hence, the number of moles of gas, a balloon inflated to 7 L of volume at STP will be 0.31 moles.

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The Arrhenius definition of an acid states that an acid ionizes or dissociates to from hydroxide ions in solution.

The definition of solutions was more given by the traditional scientist in smart solutions, which are natural solutions, like substances that - easy solutions, aqueous like bases.

In this case, Arrhenius definition of an acid states that an acid ionizes or dissociates to from hydroxide ions in solution.

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Answer:

95.45 moles

Explanation:

CO2 has mole weight  12 + 2 *16 = 44 gm/mole

4200 gm / 44 gm/mole = 95.45 moles

The possible action your solution might contain is amongst [tex]Ag^+[/tex], [tex]Pb^{2+}[/tex], or [tex]Ca^{2+}[/tex].

A solution is a homogeneous mixture of one or more solutes dissolved in a solvent.

NaCl: 20 drops of NaCl were used and no precipitate was formed.

No precipitation formed means the [tex]Cl^-[/tex] cation is soluble in water. From your chart, you might see the halide of [tex]Ag^+[/tex] and [tex]Pb^{2+}[/tex] is insoluble in water, which means they should have formed precipitation but you didn't. This means there's less possibility it contains [tex]Ag^+[/tex] or [tex]Pb^{2+}[/tex], so we are left with only [tex]Ca^{2+}[/tex]. Let's confirm it with the rest.

[tex]Na_2SO_4[/tex] : 20 drops of [tex]Na_2SO_4[/tex] were used yellow precipitate was produced.

Even though all other sulfates form precipitation ( Insoluble in water)

[tex]Na_2CO_3[/tex] : 20 drops of sodium carbonate were used and the silver-blue precipitate was produced.

It seems all of their Carbonate is insoluble in nature. ( which is our case too ).

From the above result, only the reaction with NaCl was deemed to be decisive and it indeed contains [tex]Ca^{2+}[/tex] ions. Means you are correct.

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Considering the reaction's stoichiometry and the notion of molarity, 1.167 grams of solid barium sulfate form when 32.0 mL of 0.160 M barium chloride reacts with 70.0 mL of 0.065 M sodium sulfate.

The balanced reaction is:

BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2 NaCl(aq)

The reactant that is consumed first in a chemical reaction is the limiting reagent because it stops any more reactions from taking place. The limiting reagent controls how much product is produced during the reaction.

Utilizing the reaction stoichiometry and the estimated number of moles, it is possible to identify the limiting reagent.

According to reaction stoichiometry, which describes the proportions of reagents and products in a chemical reaction, the following numbers of moles of each component are involved in the reaction:

Molarity, on the other hand, refers to how many moles of solute are dissolved in a certain volume.

Molarity is determined by the expression:

[tex]Molarity=\frac{number of moles of solute}{volume}[/tex]

Molarity is expressed in units[tex]\frac{moles}{L}[/tex].

In this case, 32.0 mL= 0.032L (being 1000 mL= 1 L) of barium chloride reacts. So, by definition of molarity, the number of moles that participate in the reaction is calculated as:

[tex]0.160 M=\frac{No. of moles of solute}{0.032L}[/tex]

No of moles of barium chloride(solute) = 0.160M × 0.032L

No of moles of barium chloride(solute) = 0.00512moles

On the other side,70.0mL= 0.070 L of 0.065 M sodium sulfate reacts. So, by definition of molarity, the number of moles that participate in the reaction is calculated as:

[tex]0.065 M =\frac{No of moles of solute}{0.070L}[/tex]

No of moles of Sodium sulfate= 0.065M × 0.070L

No of moles of Sodium sulfate = 0.0045moles

if by stoichiometry 1 mole of barium chloride reacts with 1 mole of sodium sulfate, 0.00512moles of barium sulfate reacts with how many moles of sodium sulfate?

No. of moles of sodium sulfate=

[tex]\frac{ 0.00512moles of barium sulfate * 1 mole of sodium sulfate}{1 mole of barium chloride}[/tex]

amount of moles of sodium sulfate= 0.00512 moles

But 0.00512moles of sodium sulfate are not available, 0.0045moles  moles are available. Since you have fewer moles than you need to react with  0.00512moles of barium chloride, sodium sulfate will be the limiting reagent.

Then, it is possible to determine the number of moles of barium sulfate produced by another rule of three: if by stoichiometry 1 mole of sodium sulfate produces 1 mole of barium sulfate, 0.00512 moles of sodium sulfate produces how many moles of barium sulfate?

[tex]Amt of mole of barium sulfate=\frac{0.00512 moles of sodium sulfate* 1mole of barium sulfate}{1 mole of sodium sulfate}[/tex]

amount of moles of barium sulfate=  0

Being the mass molar of barium sulfate is 233.34 g/mole, the mass-produced of the compound is calculated as:

                              = [tex]\frac{0.00512 moles * 233.34 gm}{1 mole}[/tex]

                              =1.167 gm

Hence, 1.167 gm of solid barium sulfate is formed.

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Answer:

Neither accurate not precise

Answer:

Part 1)  85.3 grams NaCl

Part 2)  8.79 x 10²³ formula units NaCl

Explanation:

(Part 1)

To find the mass of NaCl, you need to multiply the given value (1.46 moles) by the molar mass of NaCl. This measurement is the atomic masses of the elements times each of their quantities combined. In this case, there is only one mole of each element in the molecule. Moles should be located in the denominator of the conversion to allow for the cancellation of units. The final answer should have 3 sig figs to reflect the given value.

Molar Mass (NaCl): 22.99 g/mol + 35.45 g/mol
Molar Mass (NaCl): 58.44 g/mol

1.46 moles NaCl            58.44 g
---------------------------  x  ----------------  =  85.3 grams NaCl
                                        1 mole

(Part 2)

I do not know which other question the second part is referring to, so I will just use the moles given in the first part. To find the formula units, you need to multiply the given value (1.46 moles NaCl) by Avogadro's Number. This conversion represents the number of formula units found in 1 mole of the sample. The moles should be in the denominator of the conversion to allow for the cancellation of units.

Avogadro's Number:

1 mole = 6.022 x 10²³ formula units

1.46 moles NaCl         6.022 x 10²³ units
------------------------  x  -----------------------------  =  8.79 x 10²³ formula units NaCl
                                          1 mole

The force exerted between S and q is ___4 times____ the force exerted between S and p.

Coulomb's law states that , the electrostatic force of attraction or repulsion between two charged bodies is directly proportional to the product of the charges and is inversely proportional to the square of the distance between them

It is given by

[tex]\rm F = k_e \dfrac{q_1 q_2}{r^2}[/tex]

r is the distance between two bodies

It is given that

Charge q is 1 unit of distance away from the source charge S

Charge p is two times further away from the source charge S

force exerted between S and q

distance between the charges is 1 unit

[tex]\rm F_{qs} = k_e \dfrac{q_q q_s}{1^2}\\\\\rm F_{ps} = k_e \dfrac{q_p q_s}{2^2}\\[/tex]

The force exerted between S and q is _______ the force exerted between S and p.

[tex]\rm F_{qs} = k_e \dfrac{q_q q_s}{1^2} = F_{ps} = k_e \dfrac{q_p q_s}{2^2}\\\\[/tex]

Assuming the charges to be q units

Then

[tex]\rm F_{qs} = k_e \dfrac{q_q q_s}{1^2} = F_{ps} = k_e \dfrac{q_p q_s}{2^2}\\\\\\\\\dfrac {F_{qs}}{F_{ps}} = \dfrac{2^2}{1^2} = 4 \\\\\\{F_{qs}} = 4{F_{ps}}[/tex]

Therefore ,

The force exerted between S and q is ___4 times____ the force exerted between S and p.

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Answer:

[tex]\textsf {A}[/tex]

Explanation:

[tex]\textsf {The effect of a catalyst on the energy of a reaction system }\\\textbf {is that it reduces the activation energy.}[/tex]

Answer:

it reduces the activation energy (option A)

Explanation:

we know that a catalyst reduces the activation energy because it speeds up a reaction (that is what a catalyst is--a substance that speeds up a reaction [whilst leaving it unchanged chemically]. )

So, if a catalyst is speeding up the time it takes for a reaction to occur, it is logically lowering the minimum energy that is needed for the reaction to occur.

This can best be expressed in option A, because it lowers the activation energy

The number of moles of the gas at 77°C and 1.33 atm occupies a volume of 50.3 L is 2.35 moles. It can found with the help of Ideal gas equation.

The ideal gas equation is formulated as : PV = nRT.

In this equation, P refers to the pressure of the ideal gas, V is the volume of the ideal gas, n is the total amount of ideal gas that is measured in terms of moles, R is the universal gas constant, and T is the temperature.

Given ;

We know ;

Formula used ;

n = PV / RT

n = 1.33 x 50.3 / 0.081 x 350k

  =  2.35 moles.

Hence, The number of moles of the gas at 77°C and 1.33 atm occupies a volume of 50.3 L is 2.35 moles

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Answer: B

Explanation:

Answer: The reaction requires breaking one O=O bond and two H-H bonds, and then forming four O-H bonds.

The percent yield for the chemical  reaction producing sulfur trioxide is 66.51%.

Percent yield is defined as the ratio of actual yield to the theoretical yield multiplied by 100. If the actual and theoretical yield are same then the percent yield is 100%.If actual yield is less than the theoretical yield then the percent yield is less than 100%.Reason of this condition arising is the incompletion of reaction or loss of sample during recovery process.

In cases where percent yield is over 100% it indicates that more sample is recovered than the predicted amount.

For the given reaction, theoretical yield is calculated as,

128.132 g of sulfur dioxide gives 160.12 g of sulfur trioxide

∴705 g of sulfur dioxide gives 705×160.12/128.132= 881 g

Percent yield is, 586/881×100=66.51%

Therefore, the percent yield for the chemical  reaction is 66.51%.

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Answer:

The answer is "B will give up two electrons to form bonds".

Explanation:

To first solve this multiple choice question, we need to identify the Atoms, A and B.

We can do this by looking at their amount of electrons.

For instance,

A = Neon = 10 Electrons

B = Magnesium = 12 Electrons

With this information we can then look at both elements charges to see what they need to form a bond.

In this case Neon doesn't want to form a bond, since they're in a complete octet, however Magnesium does not have a complete octet. So, it wants to give up two electrons to form a bond (2+ charge shows us that).

This then shows us that Option 2, "B will give up two electrons to form bonds" is correct.

Answer:

B will give up two electrons to form bonds

Explanation:

The reason for this is that water is a polar molecule and one water molecule is attracted to the other by a hydrogen bond.

The term entropy refers to the degree of disorder in a molecule. The more disorderly a molecule is, the higher its entropy.

The fact that water is a polar molecule and one water molecule is attracted to the other by a hydrogen bond thus, two water molecules represent more entropy than two hydrogen molecules plus an oxygen molecule.

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Answer:

4.43 g Fe

Explanation:

To find the mass of iron, you need to (1) convert grams Al to moles Al (via molar mass), then (2) convert moles Al to moles Fe (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles Fe to grams Fe (via molar mass). It is important to arrange the conversions/ratios in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 3 sig figs because the given value (2.14) has 3 sig figs.

Molar Mass (Al): 26.982 g/mol

2 Al(s) + Fe₂O₃ --->  2 Fe(s) + Al₂O₃(s)

Molar Mass (Fe): 55.845 g/mol

 2.14 g Al           1 mole              2 moles Fe           55.845 g
----------------  x  -----------------  x  --------------------  x  ------------------  =  4.43 g Fe
                         26.982 g           2 moles Al             1 mole

Aluminum reacts with ferric oxide to produce iron by the thermite reaction. The mass of the iron metal that will be formed by the chemical reaction is 4.43 g Fe.

Limiting reagent has been described as reactions that are present in lesser amounts than the other reactant in the reaction that determines the amount of formation of the products and are never left in a reaction.

The balanced thermite reaction is given as:

2 Al(s) + Fe₂O₃ → 2 Fe(s) + Al₂O₃(s)

Molar mass of aluminium = 26.982 g/mol

Molar Mass of iron= 55.845 g/mol

Mass of aluminium (Al) = 2.14 grams

Here, according to the reaction 2 moles of Aluminum are needed to produce 2 moles of iron (Fe).

Moles of aluminum is calculated as:

Moles = mass ÷ molar mass

n = 2.14 ÷ 26.982

= 0.079 mol

As aluminum is the limiting reagent, it determines the formation of iron as:

2 mol Al = 2 mol Fe

0.079 mol Al = 0.079 mol Fe

Mass of iron is calculated as:

Mass = moles × molar mass

mass = 0.079 × 55.845 g/mol

= 4.411 grams

Therefore, 4.43 g Fe will be produced from 2.14 gm Al.

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Copper-plating is a chemical change in which copper ions become neutral copper atoms by accepting electrons which then are deposited on the material to be coated.

copper-plating?Copper-plating is the process by which a layer of copper is used to coat another material using the process of electrolysis.

At the molecular level, copper ions in solution accept electrons to become neutral copper atoms which then are deposited on the material, thereby coating.

This is an example of a chemical change since it us not easily reversible and new products are formed.

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The ⁴⁰₁₈X is the symbol for ⁴⁰₁₈Ar - atom and it has 18 protons, 18 electrons, and 22 neutrons.

Mass number is the sum of the numbers of protons and neutrons present in the nucleus of an atom.

In the given element,  ⁴⁰₁₈X,  Subscript 18 is the number of proton and is also equal to the number of electron. While supercript 40 is the atomic mass.

The number of neutrons is given by subtracting the proton number from the mass number.

Therefore,

Number of Neutron = Mass Number - Atomic Number

                                 = 40 - 18

                                 = 22 Neutrons

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The initial pH for the weak acid-strong base curve is higher than the initial pH for the strong acid-strong base curve. Hence, option A is correct.

Weak acids are acids that don't completely dissociate in solution.

A weak acid is an acetic acid. It has a of 1.8⋅[tex]10^{-5}[/tex]. Calculate how much it will dissociate in water. Since acetic acid is a weak acid so large part will not dissociate completely.

[tex]k_a=\frac{[CH_3COO^-]H^+]}{[CH_3COOH]}[/tex]

B is not true, it shows the titration curve for weak/strong acid titrated with a strong base. When choosing an indicator for colourimetric titration select one so that the pH jump at the equivalence point contains the interval p±1. Phenolphthalein has a p≈9, so to decide if it is a suitable indicator check if the pH jumps from 8 to 10 at the equivalence point.

C is not true either because of the very slow reaction.

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Answer:

can you post a photo? to help y with the question

Explanation: