Which of the following is a physical change?

Answer:

Alkaline earth metals or akali metals

Answer:

See explanation

Explanation:

The chlorination of benzene occurs in the presence of a Lewis acid. A Lewis acid is a compound that can accept a lone pair of electrons.

The first step in the chlorination of benzene is the formation of the ion Cl^+ which attacks the benzene ring.

This ion is formed when the Cl2 molecule undergoes heterolytic fission assisted by FeCl3 to yield FeCl4^- and Cl^+.

The Cl^+ electrophile now attacks the benzene ring to yield chlorobenzene.

Answer:

104.8 g

Explanation:

From the question given above, the following data were obtained:

Initial temperature of copper (T꜀) = 275.1 °C

Mass of water (Mᵥᵥ) = 272 g

Initial temperature of water (Tᵥᵥ) = 21 °C

Equilibrium temperature (Tₑ) = 29.7 °C

Mass of copper (M꜀) =?

NOTE:

Specific heat capacity of copper (C꜀) = 0.385 J/gºC

Specific heat capacity of water (Cᵥᵥ) = 4.184 J/gºC

Finally, we shall determine the mass of the copper in the sample. This can be obtained as follow:

Heat loss by copper = Heat gained by water

M꜀C꜀(T꜀ – Tₑ) = MᵥᵥCᵥᵥ(Tₑ – Tᵥᵥ)

M꜀ × 0.385 (275.1 – 29.7) = 272 × 4.184(29.7 – 21)

M꜀ × 0.385 × 245.4 = 1138.048 × 8.7

M꜀ × 94.479 = 9901.0176

Divide both side by 94.479

M꜀ = 9901.0176 / 94.479

M꜀ = 104.8 g

Thus, the mass of the copper in the sample is 104.8 g

Answer:

CO2

Explanation:

Carbon dioxide is a chemical compound that consists of two oxygen atoms and one carbon atom

Answer:

The initial temperature of the brass sample is 90.1°C

Note: The question is incomplete. A similar but complete question is given below :

A 52.9g sample of brass, which has a specific heat capacity of 0.375·J·g−1°C−1, is put into a calorimeter (see sketch at right) that contains 100.0g of water. The temperature of the water starts off at 15.0°C. When the temperature of the water stops changing it's 18.4°C. The pressure remains constant at 1 atm. Calculate the initial temperature of the brass sample. Be sure your answer is rounded to 2 significant digits.

Explanation:

Assuming that the calorimeter is an isolated system and that no heat is lost from the calorimeter. The total heat in the system is the sum of the heat content of the brass and that of water

Total heat lost by the brass = heat gained by the water

The quantity of heat lost or gained, Q = mcΔT

Where m = mass of the substance, c = specific heat capacity of substance, ΔT = temperature change

Heat gained by water is positive while heat lost by brass is negative

mass of brass = 52.9 g, specific heat capacity of brass = 0.375·J·g−1°C−1, ΔT = (18.4 - t °C; where t is the initial temperature), mass of water = 100.0 g, specific heat capacity of water = 4.186 J/g°C, ΔT = = 18.4 - 15.0 = 3.4 °C

Heat lost by brass z= - [ 52.9 × 0.375 × (18.4 - t)] = -365.01 + 19.8375t

Heat gained by water = 100 × 4.186 × 3.4 = 1423.24

Equating heat lost by brass to heat gained by water

-365.01 + 19.8375t = 1423.24

19.8375t = 1423.24 + 365.01

19.8375t = 1788.25

t = 90.1° C

Therefore, the initial temperature of the brass sample is 90.1°C

Explanation:

here are the answers. Note that because the pressure is constant, you can use Gay Lussac's formula

Answer:

2.75M

Explanation:

Density = mass/volume

Density of glycerol (C3H8O3) at 15°C is given as 1.2656 g/mL.

Volume of glycerol at this same temperature before dissolving in water = 50mL

Hence, using Density = mass/volume

1.2656 = mass/50

mass = 1.2656g/mL × 50mL

mass = 63.28g

Molarity of solution = number of moles (n) ÷ volume (V)

Volume of glycerol dissolved in water = 250mL = 0.250L

number of moles = mass/molar mass

Molar mass of C3H8O3 = 12(3) + 1(8) + 16(3)

= 36 + 8 + 48

= 44 + 48

= 92g/mol

n = 63.28g ÷ 92g/mol

n = 0.688mol

* Molarity = n/V

Molarity = 0.688/0.250

Molarity = 2.75M

Answer:

10.1 h

Explanation:

Let's consider the reduction half-reaction of iron from an aqueous solution of iron (III) chloride.

Fe³⁺(aq) + 3 e⁻ ⇒ Fe(s)

We can calculate the time required to produce 5.00 moles of Fe using the following relationships.

[tex]5.00molFe \times \frac{3 mole^{-} }{1molFe} \times\frac{96486C}{1mole^{-} } \times \frac{1s}{40.0C} \times \frac{1h}{3600s} = 10.1 h[/tex]

Answer:

D. Two scientists may have different underlying assumptions that lead them to different conclusions about the same thing.

Explanation:

It's all about how a person analyzes data. Some do it mathmatically while others do it logically. By doing it different ways, you may still come to the same conclusion, despite working at the problem in a different way.

Answer:

D) caring capacity

Explanation:

Answer:

D)

Explanation:

The largest population that an environment can support is by definition a carrying capacity

Answer:

2.The reaction is third order overall

Explanation:

THIS ANSWER IS CORRECT

MARK ME AS BRAINLIEST

Answer:

False

Explanation:

An object with a density greater than 1.00g/mL (greater than the density of water) will sink. An object with a density less than the density of water, will float.

If the water has a density of 1.00 g/mL. If you put an object that has a density of 0.79 g/mL into water, it will sink to the bottom, this statement is false.

The density of an actual content is its mass per unit volume. The most common symbol for density is d, but the Latin letter D can also be used.

Three of an object's most fundamental properties are mass, volume, and density. Mass describes how heavy something is, volume describes its size, and density is defined as mass divided by volume.

The density of something is a measure of how heavy it is in relation to its size. When an artifact is more dense than water, it plunges; when an object is less dense than water, it floats.

Density is a property of a substance that is independent of the amount of substance.

As in the given scenario, water is having density 1 g/mL and object in having density less then it so it will float on water.

Thus, the given statement is false as the material will not sink, rather it will float on water.

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Answer:

a hydrogen bond between the hydrogen of water and the nitrogen of the amine

a hydrogen bond between the oxygen of water and a hydrogen from the -NH2 group

Explanation:

A hydrogen bond is formed between molecules in which hydrogen is bonded to a highly electronegative element.

In amines, hydrogen is bonded to nitrogen while in water, hydrogen is bonded to oxygen. Both are highly electronegative elements hence hydrogen bonding is possible between amines and water.

This hydrogen bond may involve;

The hydrogen of water and the nitrogen of the amine

Or

The oxygen of water and a hydrogen from the -NH2 group

Answer:

isn't it 0.998

Explanation:

cause 0.998 is in the same grams / mole. I don't get

A calorimeter has been filled with 75 mL of water. The number of grams of water is 74.85 grams.

A calorimeter is an instrument that is used to measure calorimetry. It is used to measure the heat of chemical reactions and physical and chemical changes.

Mass is the quantity of matter in a physical body. Volume is the space occupied by a three-dimensional object. Mass is the quantity of matter in a physical body. The product of the compound's molar mass and the substance's moles are defined as mass.

Given, that the volume of the water is 75 mL

The temperature of the water is 25 °C

The density of water is 0.998 g/mL

To calculate the mass, the volume is multiplied by density.

Mass = volume x density

putting the values in the formula

75 x  0.998 = 74.85 grams

Thus, the grams of water that have at 25°C is 74.85 grams.

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Answer:

F. When everyone is together it gets hotter

Explanation:

Answer:

c. it lies near the equator

Answer:

Huh!?

Explanation:

explain me please

Answer:

Li(s) + H2O(l) -----> LiOH(aq) + H2(g)

Ca(s) + 2H2O(l) ---------------> Ca(OH)2(aq) + H2(g)

Explanation:

Metals react with water to yield the metal hydroxide and hydrogen gas as shown in the answer above.

The reaction equations were balanced, the number of atoms of each element on both side of the reaction equation is exactly the same.

This is the way to write a balanced reaction equation for the species shown in the question.

Answer:

See explanation

Explanation:

Equation of the reaction;

Na2CO3(aq) + 2HCl(aq) -------> 2NaCl(aq) + H2O(l) + CO2(g)

Number of moles of Na2CO3 = 21.2g/106g/mol = 0.2 moles Na2CO3

Number of moles of HCl = 21.9g/36.5g/mol = 0.6 moles of HCl

1 mole of Na2CO3 reacts with 2 moles of HCl

0.2 moles of Na2CO3 reacts with 0.2 × 2/1 = 0.4 moles of HCl

Hence Na2CO3 is the limiting reactant

Since there is 0.6 moles of HCl present, the number of moles of excess reagent=

0.6 moles - 0.4 moles = 0.2 moles of HCl

1 mole of Na2CO3 forms 1 mole of water

0.2 moles of Na2CO3 forms 0.2 moles of water

Number of molecules of water formed = 0.2 moles × 6.02 × 10^23 = 1.2 × 10^23 molecules of water

1 mole of Na2CO3 yields 1 mole of CO2

0.2 moles of Na2CO3 yields 0.2 moles of CO2

1 mole of CO2 occupies 22.4 L

0.2 moles of CO2 occupies 0.2 × 22.4 = 4.48 L at STP

Hence;

V1=4.48 L

T1 = 273 K

P1= 760 mmHg

T2 = 27°C + 273 = 300 K

P2 = 760 mmHg

V2 =

P1V1/T1 = P2V2/T2

P1V1T2 = P2V2T1

V2 = P1V1T2/P2T1

V2 = 760 × 4.48 × 300/760 × 273

V2= 4.9 L

The limiting reactant is the reactant that determines the amount of product formed in a reaction. When the limiting reactant is exhausted, the reaction stops.

Answer:

0.203 is the mean of the concentration of the HCl solution

Explanation:

You have 5 concentrations. The most appropiate result is the mean of those results. The mean is a statistical defined as the sum of each result divided by the total amount of results. For the results of the problem, the mean is:

0.210 + 0.204 + 0.201 + 0.202 + 0.197 = 1.014 / 5 =

Answer:

1.99 L

Explanation:

Given that,

A reaction produces 3.0 mol of gas, which occupies 1.46 L.

We need to find the volume of the product when 4.1 mol are produced at constant temperature and pressure.

We know that,

PV = nRT

i.e.

[tex]V\propto n\\\\\dfrac{V_1}{V_2}=\dfrac{n_1}{n_2}\\\\V_2=\dfrac{V_1n_2}{n_1}\\\\V_2=\dfrac{1.46\times 4.1}{3}\\\\V_2=1.99\ L[/tex]

So, the new volume is 1.99 L.

Answer:

2.33 mol C

Explanation:

Step 1: Write the balanced generic chemical equation

3 A ⟶ C + 4 D

Step 2: Establish the appropriate molar ratio

According to the balanced equation, the molar ratio of A to C is 3:1.

Step 3: Calculate the number of moles of C produced from 7 moles of A

We will use the previously established molar ratio.

7 mol A × 1 mol C/3 mol A = 2.33 mol C

Answer:

Magnesium.

Explanation:

Because it is in group II

The question is incomplete, the complete question is shown in the image attached to this answer

Answer:

1) K

2) F

3) Si

4) Br

Explanation:

If an element has a more negative value of electron affinity, then it has a greater ability to attract an electron.

In each of the following pairs of elements, one element has a more negative electron affinity for certain reasons.

Between K and Ca, the incoming electron in K goes into a 4s orbital which is lower in energy and more stable. For Ca, the electron goes into a 3d orbital which is more unstable.

Between Ne and F, Ne already has a filled outermost shell hence the incoming electron goes into the higher energy 3s level. In F, the electron goes into the 2p level and completes it. Hence F has a more negative electron affinity.

Let us recall that half filled and completely filled orbitals are exceptionally stable. Hence, the electron affinity of Si is more negative than that of P because in P, the electron goes into an exceptionally stable half filled orbital.

Recall that the more the value of Zeff, the more negative the electron affinity hence electron affinity increases across a period; hence, Br has a more negative value of electron affinity than Se.

Answer: The molarity of an HCl solution is 0.218 M if 43.6 mL of a 0.125 M NaOH solution are needed to titrate a 25.0 mL sample of the acid.

Explanation:

Given: [tex]V_{1}[/tex] = 43.6 mL,      [tex]M_{1}[/tex] = 0.125 M

[tex]V_{2}[/tex] = 25.0 mL,        [tex]M_{2}[/tex] = ?

Formula used to calculate the concentration of acid is as follows.

[tex]M_{1}V_{1} = M_{2}V_{2}[/tex]

Substitute the values into above formula.

[tex]M_{1}V_{1} = M_{2}V_{2}\\0.125 M \times 43.6 mL = M_{2} \times 25.0 mL\\M_{2} = 0.218 M[/tex]

Thus, we can conclude that the molarity of an HCl solution is 0.218 M if 43.6 mL of a 0.125 M NaOH solution are needed to titrate a 25.0 mL sample of the acid.

The molarity of the HCl solution used in the neutralization reaction has been 0.218 M.

The reaction of NaOH with HCl has been a neutralization reaction. The resultant will be salt and water.

In the reaction the molarity can be calculated as:

Molarity of HCl [tex]\rm[/tex][tex]\times[/tex] Volume of HCl = Molarity of NaOH

Given,

The volume of HCl solution = 25 ml

Molarity of NaOH = 0.125 M

Volume of NaOH solution = 43.6 ml

Substitute the values in the equation:

Molarity of HCl [tex]\times[/tex] 25 = 0.125 [tex]\times[/tex] 43.6

Molarity of HCl [tex]\times[/tex] 25 = 5.45

Molarity of HCl solution = [tex]\rm \dfrac{5.45}{25}[/tex]

Molarity of HCl solution = 0.218 M

The molarity of the HCl solution used in the neutralization reaction has been 0.218 M.

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Answer:

a. the proportion of elements to compounds is constant.

Answer:

Option B. The reaction will shift to the left in the direction of the reactants.

Explanation:

The equation for the reaction is given below:

CO₂ + 2H₂O <=> CH₄ + O₂

Enthalpy change (ΔH) = +890 KJ

The reaction illustrated by the equation is endothermic reaction since the enthalpy change (ΔH) is positive.

Increasing the temperature of an endothermic reaction will shift the equilibrium position to the right and decrease the temperature will shift the equilibrium position to the left.

Therefore, decreasing the temperature of the system illustrated by the equation above, will shift the reaction to the left in the direction of the reactants.

Thus, option B gives the right answer to the question.

Answer:

Option b.

Al < B < P < N

Explanation:

Electronegativity is the capacity of an atom to attract electrons.

Usually, if we look at the periodic table, the elements in the left are the ones with the least electronegativity, and as we go to the right, the electronegativity increases (this is not really exact)

There are a lot of tables of electronegativity that can be used here, we can find that:

element:    electronegativity:

    N                         3.04

    B                          2.04

    P                          2.19

    Al                          1.61

So, the order from least to greatest is:

Al, B, P, N

Then the correct option is:

b: Al < B < P < N

Answer:

Hydrogen bonding - London dispersion forces - dipole-dipole interactions

Strongest ----> Weakest

Answer:

Percent yield = 48.3%

Explanation:

The reaction is:

CCl₄  +  2HF → CF₂Cl₂ + 2HCl

1 mol of CCl₄ reacts with 2 moles of hydrofluoric acid in order to produce 1 mol of CF₂Cl₂ and 2 moles of hydrogen chloride.

HF is in excess, so the limiting reagent is the CCl₄.

We convert mass to moles:

32.9 g . 1mol / 153.8g = 0.214 moles

Ratio is 1:1. In conclussion: 0.0813 moles of CCl₄ can produce 0.0813 moles of CF₂Cl₂. We convert moles to mass, to determine the theoretical yield:

0.214 mol . 120.91g /mol = 25.8 g

Percent yield = (Yield produced /Theoretical yield) . 100

Percent yield = (12.5 g/ 25.8g) . 100 = 48.3%