Which of the following obervations would be classified as a physical change? A) Fireworks releasing light B) Antacid fizzing in water C) Steam condensing on a mirror D) Apple turning brown

Answer:

1 mole of the gas occupies 22. 4L at O0C at 1atm pressure. Hence, the correct option is C.

Explanation:

Answer:

93.15 %

Explanation:

We have to start with the chemical reaction:

[tex]CaCl_2~+~Na_2CO_3~->~CaCO_3~+~NaCl[/tex]

Now, we can balance the reaction:

[tex]CaCl_2~+~Na_2CO_3~->~CaCO_3~+~2NaCl[/tex]

Our initial data are the 15.71 g of [tex]CaCl_2[/tex], so we have to do the following steps:

1) Convert from grams to moles of [tex]CaCl_2[/tex] using the molar mass (110.98 g/mol).

2) Convert from moles of [tex]CaCl_2[/tex] to moles of [tex]CaCO_3[/tex] using the molar ratio. ( 1 mol [tex]CaCl_2[/tex]= 1 mol of [tex]CaCO_3[/tex]).

3) Convert from moles of [tex]CaCO_3[/tex] to grams of [tex]CaCO_3[/tex] using the molar mass. (100 g/mol).

[tex]15.71~g~CaCl_2\frac{1~mol~CaCl_2}{110.98~g~CaCl_2}\frac{1~mol~CaCO_3}{1~mol~CaCl_2}\frac{100~g~CaCO_3}{1~mol~CaCO_3}=14.16~g~CaCO_3[/tex]

Finally, we can calculate the yield percent:

[tex]%~=~\frac{13.19~g~CaCO_3}{14.16~g~CaCO_3}*100=93.15~%[/tex]

I hope it helps!

The percentage yield obtained when excess sodium carbonate, Na₂CO₃, is added to a solution containing 15.71 g CaCl₂ is 93.2%

Molar mass of CaCl₂ = 40 + (35.5×2) = 111 g/mol

Mass of CaCl₂ from the balanced equation = 1 × 111 = 111 g

Molar mass of CaCO₃ = 40 + 12 + (16×3) = 100 g/mol

Mass of CaCO₃ from the balanced equation = 1 × 100 = 100 g

SUMMARY

From the balanced equation above,

111 g of CaCl₂ reacted to produce 100 g of CaCO₃

From the balanced equation above,

111 g of CaCl₂ reacted to produce 100 g of CaCO₃.

Therefore,

15.71 g of CaCl₂ will react to produce = [tex]\frac{15.71 * 100}{111} \\\\[/tex] = 14.15 g of CaCO₃.

Thus, the theoretical yield of of CaCO₃ is 14.15 g

Actual yield of CaCO₃ = 13.19 g

Theoretical yield of CaCO₃ = 14.15 g

[tex]Percentage yield = \frac{Actual}{Theoretical} * 100\\\\= \frac{13.19}{14.15} * 100\\\\[/tex]

Therefore, the percentage yield of the reaction is 93.2%

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Answer: The molecules in the thermometer's liquid spread apart.

Explanation:

Mercury is the only metal that remains liquid at room temperature. It has a high coefficient of expansion therefore the its level rises when exposed to a temperature range. It can detect a slight change in temperature. It has a high  boiling point.

When the thermometer is placed in the water to measure the temperature, the molecules of thermometer liquid that is mercury only will spread due to high coefficient of expansion. This can be seen as rise in temperature.

Answer:

B

Explanation:

Just did the test

Answer:

Chemical Change

Explanation:

Physical change normally mean that the change can revert back to its orginal state, which in this case that is not possible therfore it is a chemical change.

Answer:

1. Acid-Base Reaction

Explanation:

Fe(OH)2(s) + HCl(aq) = FeCl2(aq) + H2O(l)

base               acid

This a reaction between base and acid.

Ferrous hydroxide is an inorganic alkaline compound whereas hydrochloric acid is an acid. The reaction between Fe(OH)₂and HCl is an acid-base reaction. Thus, option 1 is correct.

An acid-base reaction is a chemical change that occurs and takes place when the reactant constitutes an acid and a base. They are characterized by the exchange of protons that results in the formation of conjugate bases and acids or salt.

The acid-base chemical reaction is shown as,

Fe(OH)₂(s) + HCl(aq) ⇒ FeCl₂(aq) + H₂O(l)

Here, ferrous hydroxide is a base with hydroxide ions and hydrochloric acid is an acid with hydrogen ions. HCl donates its proton to form water molecules with hydroxide ions of ferrous hydroxide.

Therefore, in option 1. the reaction is an acid-base reaction.

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Answer: 1.311 × 10^18 photons are produced in each pulse

Explanation: Please see the attachments below

Answer:

Explanation:

70% (vol/vol) means

cotnaimns 70 %(vol/vol) 70 ml of isoprapnol is there in 100 ml of Rubbing sold alcohol.

if it is 200 ml then obvouly it has the 70*2 =140 ml of isoproanol  required.

Alcohol is an organic compound that when rubbed on the skin it evaporates quickly leaving a cool effect on the skin. The reason why it evaporates is because it has loosely bound molecules and a low boiling temperature.

The volume of pure isopropanol required to produce a 200-ml bottle of rubbing alcohol is 140 ml

From the question:

Alcohol sold contains 70%(vol/vol). This means 70 ml of the solute of isopropanol can be found in 100 ml of solution.

Hence:

100ml of solution = 70ml of isopropanol

200ml of solution = ?

Cross Multiply

200 ml x 70 ml / 100 ml

= 140 ml

Therefore, the volume of pure isopropanol required to produce a 200-ml bottle of rubbing alcohol is 140 ml

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Answer:

H2CO3 = 2H+ + CO3-

Explanation:

It is simply what carbonic acid breaks down into when placed in water. Since carbonic acid is made up of H and CO3, these are the products.

Answer:

The rates of decay of radioactive elements

Explanation:

The age of a rock in years is called its absolute age. Geologists find absolute ages by measuring the amount of certain radioactive elements in the rock. When rocks are formed, small amounts of radioactive elements usually get included.

Answer:

Na₂SO₄

Explanation:

Barium nitrate, Ba(NO₃)₂ produce precipitate with SO₄²⁻, CO₃²⁻. That means the precipitate could be obtained from Na₂SO₄ and Na₂CO₃.

Also, magnesium nitrate, Mg(NO₃)₂, produce precipitate just with CO₃²⁻. As the unknown solution produce no precipitate, the unknown compound is:

Na₂SO₄

Answer:

Explanation:

it is based on le chatliers principles

the left side of reaction you have 4 moles , where as at the right hand side you have 2 moles,,,,

so when you increase the pressure the reaction will shift towards the lower moles producing reaction that is reaction move towards forward in you case.

Answer:

[tex]\large \boxed{\text{-486 kJ}}[/tex]

Explanation:

You calculate the energy required to break all the bonds in the reactants.

Then you subtract the energy needed to break all the bonds in the products.

                      2H₂   +   O₂ ⟶ 2H-O-H

Bonds:          2H-H    1O=O       4H-O

D/kJ·mol⁻¹:     436      498          464

[tex]\begin{array}{rcl}\Delta H & = & \sum{mD_{\text{reactants}}} - \sum{nD_{\text{products}}}\\& = & 2 \times 436 +1 \times 498 - 4 \times 464\\&=& 1370 - 1856\\&=&\textbf{-486 kJ}\\\end{array}\\\text{The enthalpy of reaction is $\large \boxed{\textbf{-486 kJ}}$}.[/tex]

Answer:

I think that the fire will continue burning, because the oil and water don't mix and the water is heavier (denser) than oil, so the oil will go up and the fire with it. That's why because the gas station have sand instead of water

Water is heavier than oil. Because oil is lighter and immiscible with water, it will form a separate layer above the surface of the water and continue to burn when water is poured on a large oil fire. As a result, the fire won't be put out.

A small amount of water will instantly sink to the bottom of a pan or deep fryer filled with hot, burning oil and explode there. The Scientific American claims that the characteristics of oils explain why they do not mix with water.

Oil or petroleum-related fires cannot be put out with water. Water sinks below the oil because it is heavier than oil and does not float, allowing the fire to continue to burn. Oil and petroleum fires can be put out with fire extinguishers or sand.

The temperature of the burning substance is lowered by water. The fire goes out when the temperature drops below the burning substance's ignition temperature. Here, the water serves as an acclimatizer.

Thus,  it will form a separate layer above the surface of the water and continue to burn when water is poured on a large oil fire.

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Answer:

[tex]M=0.213M[/tex]

Explanation:

Hello,

In this case, for each nitrate-based salt, we compute the nitrate moles as shown below:

[tex]n_{NO_3^-}=20.00gCa(NO_3)_2*\frac{1molCa(NO_3)_2}{164.088 gCa(NO_3)_2} *\frac{2molNO_3^-}{1molCa(NO_3)_2} =0.244molNO_3^-[/tex]

[tex]n_{NO_3^-}=10.00gNaNO_3*\frac{1molNaNO_3}{84.9947 gNaNO_3} *\frac{1molNO_3^-}{1molNaNO_3} =0.118molNO_3^-[/tex]

[tex]n_{NO_3^-}=50.00gAl(NO_3)_3*\frac{1molAl(NO_3)_3}{212.996gAl(NO_3)_3} *\frac{3molNO_3^-}{1molAl(NO_3)_3} =0.704molNO_3^-[/tex]

We notice calcium nitrate has two moles of nitrate ion, sodium nitrate has one and aluminium nitrate has three. Hence we add the moles to obtain the total moles nitrate ion:

[tex]n_{NO_3^-}^{Tot}=0.244+0.118+0.704=1.066molNO_3^-[/tex]

Finally, we compute the molarity:

[tex]M=\frac{1.066molNO_3^-}{5.00L} \\\\M=0.213M[/tex]

Regards.

Answer:  [tex]H_2PO_4[/tex] and [tex]H_3PO_4[/tex]

Explanation:

According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.

For the given reaction:

[tex]H_2PO_4^-+H_2O\rightleftharpoons H_3PO_4+OH^-[/tex]

Here, [tex]H_2O[/tex] is loosing a proton, thus it is considered as an acid and after losing a proton, it forms [tex]OH^-[/tex] which is a conjugate base.

Similarly , [tex]H_2PO_4^-[/tex] is gaining a proton, thus it is considered as an base and after gaining a proton, it forms [tex]H_3PO_4[/tex] which is a conjugate acid.

Thus [tex]H_2PO_4[/tex] and [tex]H_3PO_4[/tex] is a conjugate acid-base pair in the reaction represented by the equation below

The Bronsted-Lowry conjugate acid-base hypothesis defines an acid as a substance that loses protons and donates them to another chemical to produce conjugate base, and a base as a substance that takes protons to generate conjugate acid.

Thus, a proton is being lost, making it an acid, and once a proton is lost, a conjugate base is formed. Similar to that, is gaining a proton, making it a base, and then it produces a conjugate acid after gaining a proton.

The Brnsted-Lowry hypothesis, often known as the proton theory of acids and bases, is an independent theory of acid-base reactions that was put forth in 1923 by Johannes Nicolaus Brnsted and Thomas Martin Lowry.

This theory's central idea is that when an acid and a base interact, the acid creates its conjugate base and the base creates its conjugate acid by exchanging a proton (the hydrogen cation, or H+).

Thus, The Bronsted-Lowry conjugate acid-base hypothesis defines an acid as a substance that loses protons and donates them to another chemical to produce conjugate base, and a base as a substance that takes protons to generate conjugate acid.

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Answer:

85.34g of NH3

Explanation:

Step 1:

The balanced equation for the reaction. This is given below:

N2 + 3H2 —> 2NH3

Step 2:

Determination of the number of moles of NH3 produced by the reaction of 2.51 moles of N2. This is illustrated below:

From the balanced equation above,

1 mole of N2 reacted to produce 2 moles of NH3.

Therefore, 2.51 moles of N2 will react to produce = (2.51 x 2)/1 = 5.02 moles of NH3.

Therefore, 5.02 moles of NH3 is produced from the reaction.

Step 3:

Conversion of 5.02 moles of NH3 to grams. This is illustrated below:

Molar mass of NH3 = 14 + (3x1) = 17g/mol

Number of mole of NH3 = 5.02 moles

Mass of NH3 =..?

Mass = mole x molar Mass

Mass of NH3 = 5.02 x 17

Mass of NH3 = 85.34g

Therefore, 85.34g of NH3 is produced.

Answer:

1177.88g of C3H8

Explanation:

We'll begin by writing the balanced equation for the reaction. This is given below:

C3H8 + 5O2 —> 3CO2 + 4H2O

Next we shall determine the number of mole of C3H8 required to produce 80.3 moles of CO2. This is illustrated below:

From the balanced equation above,

1 mole of C3H8 reacted to produce 3 moles of CO2.

Therefore, Xmol of C3H8 will react to produce 80.3 moles of CO2 i.e

Xmol of C3H8 = 80.3/3

Xmol of C3H8 = 26.77 moles

Finally, we shall convert 26.77 moles of C3H8 to grams.

Molar mass of C3H8 = (3x12) + (8x1) = 44g/mol

Mole of C3H8 = 26.77 moles

Mass of C3H8 =..?

Mass = mole x molar mass

Mass of C3H8 = 26.77 x 44

Mass of C3H8 = 1177.88g

Therefore, 1177.88g of C3H8 are needed for the reaction

Answer:

Mass ratio of sulfur and oxygen in compounds A and B is 3:2 which confirms that the mass ratios in the two compounds are simple multiples of each other

Explanation:

This question seeks to establish/confirm the law of multiple proportions which  posits that elements combine to form different substances which are whole number multiples of each other. Best example of this plays out in the formation of several oxides of the same element. Looking at the ratio in which the elements combine in each of the oxides, we can assume that these ratios are simple whole number multiples of each other.

Now back to the question.

In substance A, we have 6 g of sulfur combining with 5.99 g of oxygen

Now, lest us calculate the ratio of the mass of sulfur to that of oxygen = 6g/5.99g = 1

Now let us calculate the mass ratio of sulfur to oxygen in the second compound = 8.6/12.88 = 0.668

Now the ratios in both compounds are 1 to 0.668. 0.668 to fraction is approximately 1/1.5.

So therefore, the ratio we are having would be 1:1/1.5 or 1:0.668

This is same as 1/(1÷1.5) which is 1.5/1 or simply 3/2

This gives a ratio of approximately 1.5 to 1 or 3 to 2

The ratio 3 to 2 indicates that the mass ratios in both com pounds are simple multiples of each other

Answer:

The appropriate reagent is: H3PO2.

Explanation:

H3PO2 is in charge of eliminating the amino group by diazotization, remember that the amino group had previously achieved bromination at positions m; that is to say that it achieved in the beginning that the three bromine atoms of 1,2,4 tribromobenzene were introduced in the meta positions among themselves, which finally corresponds as part of the last reaction to the 1,3,5-tribromobenzene position.

Answer: The Gibbs free energy of the reaction is -114629.4 J

Explanation:

To calculate the Gibbs free energy of the reaction, we use the equation:

[tex]\Delta G^o=-RT\ln K_{eq}[/tex]

where,

[tex]\Delta G^o[/tex] = Gibbs free energy of the reaction = ?

R = Gas constant = [tex]8.314 J/K.mol[/tex]

T = temperature of the reaction = 298 K

[tex]K_{eq}[/tex] = equilibrium constant of the reaction = [tex]1.24\times 10^{20}[/tex]

Putting values in above equation, we get:

[tex]\Delta G^o=-(8.314J/mol.K\times 298K\times \ln (1.24\times 10^{20}))\\\\\Delta G^o=-114629.4J[/tex]

Hence, the Gibbs free energy of the reaction is -114629.4 J

Answer: Thus the mass, in grams, of 27 moles of smooth muscle myosin is 12960000 grams

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass, occupies 22.4 L at STP  contains avogadro's number [tex](6.023\times 10^{23})[/tex] of particles.

Molecular mass of protein = 480,000 g/mol

Thus 1 mole of protein weighs = 480,000 g

So 27 moles of protein weighs = [tex]\frac{480,000}{1}\times 27=12960000g[/tex]

Thus the mass, in grams, of 27 moles of smooth muscle myosin is 12960000 grams

Answer:

CATION

Explanation:

It's one is the action and the mother is a cation.

Answer: D

Explanation: The elements in two compunds switch places

Answer:

The correct answer is 81.52 percent.

Explanation:

Based on the given information, the boiling point of pentane is 36 degree C and the boiling point of ethanol is 78 degree C. The density of pentane and ethanol is 0.63 g/ml and 0.79 g/ml. The vapor pressure of pentane at 57.2 degree C is 1439 torr and the vapor pressure of ethanol at 57.2 degree C is 326 torr.  

In the given case, 50 percent pentane by mass signifies that mass of pentane is 50 grams. Thus, the mass of ethanol will be 100-50 = 50 grams.  

The moles or n can be calculated by using the formula,  

n = weight/molecular mass

The molecular mass of pentane is 72.15 g per mol and the molar mass of ethanol is 46.07 g/mol.  

The moles of pentane is,  

= 50 g/72.15 g/mol = 0.6930 mol

The moles of ethanol is,  

= 50 g/46.07 g/mol = 1.0853 mol

The mole fraction of pentane is,  

= 0.6930 mol / (0.6930 + 1.0853) mol = 0.3897  

The mole fraction of ethanol is,  

= 1.0853 mol / (0.6930 + 1.0853) mol = 0.6103

Now the vapor pressure of solution will be,  

= pressure of pentane * mole fraction of pentane + pressure of ethanol * mole fraction of ethanol

= (1439 * 0.3897) + (326 * 0.6103)

= 759.736 torr

The vapor pressure of pentane within the solution,  

= vapor pressure of pentane * mole fraction of pentane

= 1439 torr * 0.3897

= 560.778 torr

The fraction of pentane is,  

= 560.778 / 759.736 = 0.738

Let us assume that the total mole is 1, the mole fraction of pentane is 0.738, so the mole fraction of ethanol will become, 1-0.738 = 0.262

The mass of pentane = 0.738 * 72.15 = 53.2467

The mass of ethanol = 0.262 * 46.07 = 12.07034

The percent by mass of pentane in new solution will be,  

Mass% = mass of pentane/Total mass * 100%

= 53.2467/(53.2467 + 12.07034) * 100%

= 53.2467/65.31704 * 100 %

= 81.52 %

Answer:

H2 consumed 4.22 mol

N2 produced 59.107 g

Explanation:

Balanced equation:

2NO (g) + 2H2 (g) N2 (g) + 2H2O (l)

H2O MW = 18.02 g/mol

N2 MW = 28.01 g/mol

To determine the moles of H2O produced, the following formula should be used:

[tex]MW=\frac{mass}{mol}[/tex]

The value of moles is cleared:

[tex]mol=\frac{mass}{MW} =\frac{76.2g}{18.02\frac{g}{mol} } =4.22 mol[/tex]

2 mol H2      ⇒ 1 mol N2

4.22 mol H2 ⇒ X

[tex]X=\frac{4.22mol*1 mol}{2 mol} =2.11 mol[/tex]

To calculate the mass of H2 consumed, the molecular weight equation is used again:

[tex]mass=MW*mol=28.013\frac{g}{mol}*2.11mol=59.107g[/tex]

Answer:

The correct answer is 32.2 grams.

Explanation:

Based on the given information, the enthalpy of formation for aluminum oxide is 1676 kJ/mol. It signifies towards the energy that is required to generate aluminum and oxygen, and both of these exhibit zero enthalpy of formation. Therefore, the ΔHreaction is the required energy to generate 2 moles of aluminum. Thus, the energy needed for the formation of single mole of aluminum is,  

ΔHrxn = 1676/2 = 838 kJ/mol

Q or the energy input mentioned in the given case is 1000 kJ. Therefore, the number of moles of Al generated is,  

(1000 kJ) / (838 kJ/Al mole) = 1.19 moles of Aluminum

The grams of aluminum produced can be obtained by using the formula,  

mass = moles * molecular mass

= 1.19 * 26.98

= 32.2 grams.  

In the thermal decomposition of aluminum oxide, the transference of 1.000 × 10³ kJ of heat can produce 32.19 g of Al.

A thermochemical equation is a balanced stoichiometric chemical equation that includes the enthalpy change.

Al₂O₃(s) ⇒ 2 Al(s) + 3/2 O₂(g)     ΔH rxn = 1676 kJ

According to the thermochemical equation, 2 moles of Al are formed when 1676 kJ of heat is transferred.

1.000 × 10³ kJ × (2 mol Al/1676 kJ) = 1.193 mol Al

The molar mass of Al is 26.98 g/mol.

1.193 mol × 26.98 g/mol = 32.19 g

In the thermal decomposition of aluminum oxide, the transference of 1.000 × 10³ kJ of heat can produce 32.19 g of Al.

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Answer:

Explanation:

Step 1: Data given

The equilibrium constant, Kc, for the following reaction is 4.76 * 10^-4 at 431 K

The equilibrium concentration of Cl2(g) is  0.233 M

Step 2: The balanced equation

PCl5(g)  ⇄ PCl3(g) + Cl2(g)

Step 3: The initial concentration

[PCl5]= Y M

[PCl] = 0M

[Cl2] = 0M

Step 4: Calculate the concentration at equilibrium

[PCl5] = Y + X M = Y - 0.233 M

[PCl]= XM = 0.233 M

[Cl2]= XM = 0.233 M

Step 5: Define Kc

Kc =  [Cl2]* [PCl3] / [PCl5]

4.76 * 10^-4 = 0.233² / (Y -0.233)

0.000476 = 0.05429 / (Y - 0.233)

Y - 0.233 = 0.05429 / 0.000476

Y - 0.233 = 114.05 M

Y = 114.283 M = the initial concentration

The concentration of PCl5 at the equilibrium is 114.05 M

Answer:

[tex]Q=-361.56kJ[/tex]

Explanation:

Hello,

In this case, the decomposition of hydrogen peroxide is given by:

[tex]2H_2O_2\rightarrow 2H_2O+O_2[/tex]

Which occurs in gaseous phase, therefore the enthalpy of reaction is:

[tex]\Delta _rH=2\Delta _fH_{H_2O}-2\Delta _fH_{H_2O_2}[/tex]

Oxygen is not included as it is a pure element. The enthalpies of formation for both hydrogen peroxide and water are -136.11 and -241.83 kJ/mol respectively, so we compute the enthalpy of reaction:

[tex]\Delta _rH=2(-241.83kJ/mol)-2(-136.11kJ/mol)=-211.44kJ/mol[/tex]

Then, the total heat that is released for 1.71 mol of hydrogen peroxide is:

[tex]Q=n*\Delta _rH=1.71mol*-211.44kJ/mol\\\\Q=-361.56kJ[/tex]

Whose sign means a released heat.

Regards.

Answer:

Chemical reactions, kinetics, organic chemistry

Explanation:

You might study the chemical reaction, learn about the differences between products and reactants, about delta H and exothermic and endothermic reactions. You may also study Kinetics by studying the rates of reactions with certain chemicals in a maple's enzymatic processes.

Another thing that you might learn about is organic chemistry. The glucose molecules, carbohydrates, lipids, nucleic acids, all have a structure based on the Carbon atom. You can learn about the specific structures of some chemicals that are involved in photosynthesis and simple hydrocarbons that are involved in photosynthetic/bio-synthetic pathways.

There's probably a lot more - but these are the most basic things I could think of.

Cathode ray experiments of the following provides evidence to support Thomson's hypothesis about electrons.

Rutherford's gold leaf experiment demonstrated that the atom is essentially empty space with such a tiny, compact, positively-charged nucleus. Thomson had proposed the plum pie model of the atom, which featured negatively-charged electrons buried within a favorably "soup." Since most of the alpha particles flow through an atom directly without being deflected, contrary to what Thomson's model predicted, the majority of a space inside of an atom is empty. As a result, the Thomson model of a molecule was disproved.

According to Thomson's model, every atom is made up of negative charges "plums" surrounded in positively charged "pudding," or electrons with a soup of positive ion to balance their negative charges. Hans Geiger and Arthur Marsden's 1909 gold foil test refuted the 1904 Thomson model.

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