Stoichiometry - Chemistry​

Answer:

The percentage efficiency of the electrical element is approximately 82.186%

Explanation:

The given parameters are;

The thermal energy provided by the stove element, [tex]H_{supplied}[/tex] = 3.34 × 10³ J

The amount thermal energy gained by the kettle, [tex]H_{absorbed}[/tex]  = 5.95 × 10² J

The percentage efficiency of the electrical element in heating the kettle of water, η%, is given as follows;

[tex]\eta \% = \dfrac{H_{supplied} - H_{absorbed} }{H_{supplied}} \times 100[/tex]

Therefore, we get;

[tex]\eta \% = \dfrac{3.34 \times 10^3 - 5.95 \times 10^2}{3.34 \times 10^3} \times 100 = \dfrac{549}{668} \times 100 \approx 82.186 \%[/tex]

The percentage efficiency of the electrical element, η% ≈ 82.186%.

Answer:

Organ System

Explanation:

These organs are helping each other process food and therefore be an Organ System

Answer:

[tex]\boxed {\boxed {\sf 55.76756 \ amu}}[/tex]

Explanation:

The average atomic mass is the sum of the product of the given masses and their abundances. We have to complete two steps for each isotope, then add all the products together.

Fe-54

Convert the percent abundance to a decimal by dividing by 100.

Multiply the abundance as a decimal by the mass number. This is the number after the element in the isotope symbol (54 amu).

Fe-56

Convert the percent to a decimal.

Multiply the decimal by the mass number (56 amu).

Fe-58

Convert the percent to a decimal.

Multiply by the mass number (58 amu).

Average Atomic Mass

Add all the products together to find the average atomic mass.

The average atomic mass given the percent abundance is 55.7656 atomic mass units.

Answer:

3 Protons, 2 Neutrons, & 3 Electrons. Is the charge of this atom positive, negative, or neutral?

Explanation:

Put these atoms in order from most negative overall charge to least negative

overall charge.

11 Atom X: 104 protons, 102 electrons

11 Atom B: 24 protons, 18 electrons

1 Atom Q: 15 protons, 16 electrons

11. Atom P: 7 protons, 10 electrons

Answer: Yes! you're all good. Alkali metals in group 1 are the most metallic :)

Answer:

the red arrow shows that the change in enthalpy is positive

From the energy diagram, it is clear that, the enthalpy of the reaction is positive and it is an endothermic reaction.

An endothermic reaction is a chemical reaction that absorbs heat from its surroundings, resulting in a decrease in temperature of the surroundings. In other words, energy is taken in by the reaction from the environment.

During an endothermic reaction, the reactants absorb energy in the form of heat, light, or electricity to break the bonds between their atoms and form new bonds to create products.

The amount of energy absorbed by the reactants is greater than the energy released by the products. This energy difference is usually expressed as the enthalpy change (∆H) of the reaction, which is positive for endothermic reactions.

Here, the energy of products is higher than that of reactants and hence option A is correct.

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Answer:

Physical chemistry is the study of macroscopic, and particulate phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics, analytical dynamics and chemical equilibrium while environmental chemistry is the study of chemical processes that occur in water, air, terrestrial and living environments, and the effects of human activity on them. 

Physical chemistry is the area of chemistry that deals with how materials interact and change. The scientific study of chemical and biological phenomena that take place in the environment is known as environmental chemistry.

Physical chemistry attempts to quantify, correlate, and explain the quantitative features of reactions by focusing, in contrast to other branches, on the physics principles that underlie all chemical interactions (such as the gas laws).

While environmental chemistry is the study of chemical species' sources, reactions, movement, impacts, and fates in the air, soil, and water environments, as well as the impact of human activity and biological activity on these, can be summed up as the field of chemical ecology.

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Answer:

Brownian moment means zig-Zag motion of particals Randomly anywhere in the free space or in fluids

Viruses are known as obligatory parasites as they only become active and multiply when inside a host. Viruses are inactive when they are outside.

Answer:

Swimming pool is an example of solution

Explanation:

It has water (solvent) and dissolve ion (solute)

Answer:

it is a solution

Explanation:

the combining of (water and Cl and other pool chemicals) make it a solution.

Answer:

For 1: 6.68 g of nitrogen dioxide will contain [tex]8.73\times 10^{22}[/tex] number of molecules

For 2: The given amount of nitrogen dioxide molecules has a mass of 41.31 g.

Explanation:

According to the mole concept:

1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

We are given:

Mass of nitrogen dioxide = 6.68 g

Molar mass of nitrogen dioxide = 46 g/mol

Putting values in equation 1, we get:

[tex]\text{Moles of nitrogen dioxide}=\frac{6.68g}{46g/mol}=0.145mol[/tex]

Using above concept:

If 1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules

So, 0.145 moles of nitrogen dioxide will contain = [tex](0.145\times 6.022\times 10^{23})=8.73\times 10^{22}[/tex] number of molecules

Hence, 6.68 g of nitrogen dioxide will contain [tex]8.73\times 10^{22}[/tex] number of molecules

We are given:

Molecules of nitrogen dioxide = [tex]5.41\times 10^{22}[/tex] molecules

Using the above concept:

If [tex]6.022\times 10^{23}[/tex] number of molecules are present in 1 mole of a compound

So, [tex]5.41\times 10^{22}[/tex] number of molecules will be present in = [tex]\frac{1mol}{6.022\times 10^{23}}\times 5.41\times 10^{22}=0.898[/tex] moles of nitrogen dioxide

We know, molar mass of nitrogen dioxide = 46 g/mol

Using equation 1:

[tex]0.898mol=\frac{\text{Mass of nitrogen dioxide}}{46g/mol}\\\\\text{Mass of nitrogen dioxide}=0.898mol\times 46g/mol=41.31g[/tex]

Hence, the given amount of nitrogen dioxide molecules has a mass of 41.31 g.

Answer:

Gases do not have a definite shape or volume because the molecules in gases are very loosely packed, they have large intermolecular spaces and hence they move around. ... The particles of solid are closely packed and occupy less space while particles of gases are loosely packed and occupy the complete space available.

Explanation:

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Answer:

When gases in containers are heated, their molecules increase in average speed. This means that they exert a greater force when they collide with the container walls, and also collide with the walls more frequently. The gas is therefore under greater pressure when its temperature is higher.

Answer:

v = 3,000,000,000 m/s

Explanation:

v = f *L

v = 3,000,000 * 1000

v = 3,000,000,000 m/s

Answer:

i am so sorry. i do not have a answer but i am trying to find questioms i can answer

Answer:

84.324  gram

Explanation:

mass = no of moles * molar mass

mass = 0.468 * 180.18 = 84.324 grams

Answer:

3. The mass of ethanol required is approximately 0.522869 g

The mass of ethanoic acid required is approximately 0.68156 g

4. The mass of iron (III) oxide required is approximately 285.952.189.095 tonnes

5. The mass of silver nitrate required is approximately 14.53 grams

6. The mass of copper oxide that would be needed is approximately 31.86 grams

7. a. The mass of the precipitate, Zn(OH)₂ formed is approximately 49.712 grams

b. The mass of the precipitate, Al(OH)₃ formed is approximately 13 grams

c. The mass of the precipitate, Mg(OH)₂, formed is approximately 14.579925 grams

Explanation:

3. The 1 mole of ethanol and 1 mole of ethanoic acid combines to form 1 mole of ethyl ethanoate

The number of moles of ethyl ethanoate in 1 gram of ethyl ethanoate, n = 1 g/(88.11 g/mol) = 1/88.11 moles

∴ The number of moles of ethanol = 1/88.11 moles

The number of moles of ethanoic acid = 1/88.11 moles

The mass of ethanol = (46.07 g/mol) × 1/88.11 moles = 0.522869 g

The mass of ethanoic acid in the reaction = 60.052 g/mol × 1/88.11 moles ≈ 0.68156 g

4. 1 mole of iron(III) oxide reacts with 1 mole of CO₂ to produce 1 mole of iron

The number of moles in 100 tonnes of iron= 100000000/55.845 = 1790670.60614 moles

The mass of iron (III) oxide required = 159.69 × 1790670.60614 = 285952189.095 g ≈ 285.952.189.095 tonnes

5. The number of moles of NaCl in 5 grams of NaCl = 5 g/58.44 g/mol = 0.0855578371 moles

The mass of silver nitrate required, m = 169.87 g/mol × 0.0855578371 moles ≈ 14.53 grams

6. The number of moles of CuSO₄·5H₂O in 100 g of CuSO₄·5H₂O = 100 g/(249.69 g/mol) ≈ 0.4005 moles

The mass of copper oxide required, m = 79.545 g/mol × 0.4005 moles ≈ 31.86 grams

7. a. The number of moles of NaOH in the reaction = 20 g/(39.997 g/mol) ≈ 0.5 moles

2 moles of NaOH produces 1 mole of Zn(OH)₂

0.5 moles of NaOH will produce 0.5 mole of Zn(OH)₂

The mass of 0.5 mole of Zn(OH)₂ = 0.5 mole × 99.424 g/mol = 49.712 grams

The mass of the precipitate, Zn(OH)₂ formed = 49.712 grams

b. 6 moles of NaOH produces 2 moles Al(OH)₃

20 g, or 0.5 mole of NaOH will produce (1/6) mole of Al(OH)₃

The mass of the precipitate, Al(OH)₃ formed, m = 78 g/mol×(1/6) moles = 13 grams

c. 2 moles of NaOH produces 1 mole of Mg(OH)₂, therefore;

20 g or 0.5 moles of NaOH formed (1/4) mole of Mg(OH)₂

The mass of the precipitate, Mg(OH)₂, formed, m = 58.3197 g/mol × (1/4) moles = 14.579925 grams

Answer:

Explanation:

i will show in details how 2 do the 1st Q n u can do the rest by following the way how it is done

3. given C^2H^5OH + CH^3CO^2H → CH^3CO^2C^2H^5 + H^2O

molar ratio of ethanol, ethanoic acid and ethyl ethanoate is 1 : 1 : 1

so mass = no. of moles * molecular mass

for same no. of moles, mass / molecular mass is the same

molecular mass of CH^3CO^2C^2H^5 = 12+1*3+12+16*2+12*2+5*1 = 88

molecular mass of C^2H^5OH = 12*2+1*5+16+1 = 46

molecular mass of CH^3CO^2H = 12+1*3+12+16*2+1 = 60

1 g of ethyl ethanoate = 1/88 mole

it requires 1/88*46 = 0.5227 g of ethanol; and

1/88*60 = 0.6818 g of ethanoic acid

to react together to form 1 g of ethyl ethanoate

Answer:

See explanation

Explanation:

Calcium carbide reacts with water to yield acetylene gas and calcium hydroxide as follows;

CaC2(s)+2H2O(g)⇋Ca(OH)2(s)+C2H2(g)

This now shows us that the equation as written in the question is wrong. Since the equation for the reaction of calcium carbide and water as shown in the question is wrong, the equation can not be balanced.

Answer:

Narcotics

I think ans is

Explanation:

tropicaia

Ecstasy, also known as MDMA, is used recreationally, so it can be called a club drug. However, it is illegal in the US, so it would be considered a narcotic as well. The effects it has are also of the stimulant variety, so they would fall under that category as well. It is definitely not a depressant.

Answer:

39.02amu

Explanation:

According to this question, there are four (4) isotopes for element X with the following relative abundance:

Isotope 1 = 9.67%, mass no: 38

Isotope 2 = 78.68%, mass no: 39

Isotope 3 = 11.34%, mass no: 40

Isotope 4 = 0.31%, mass no: 41

To find the average atomic mass of element X, we multiply each isotopes' relative abundance by its mass no and find the sum as follows:

We convert each percentage to decimal abundance:

Isotope 1 = 9.67% = 0.0967

Isotope 2 = 78.68% = 0.7868

Isotope 3 = 11.34% = 0.1134

Isotope 4 = 0.31% = 0.0031

(0.0967 × 38) + (0.7868 × 39) + (0.1134 × 40) + (0.0031 × 41)

3.6746 + 30.6852 + 4.536 + 0.1271

Average atomic mass = 39.02amu

Answer:

An ice cube melting is a physical change because melting doesn't change the composition of the element. Paper burning is a chemical change because combustion occurs. Bubbles forming in a soda does involve chemical changes. Hard-boiling an egg is a chemical change because the egg's composition changed.

Answer:

80 m/s.

Explanation:

NOTE: This is a physics question. However, the solution to the question given below:

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

Acceleration (a) = 2 m/s²

Initial velocity (u) = 20 m/s

Time (t) = 30 s

Final velocity (v) =?

The final velocity of the train can be obtained as shown below:

v = u + at

v = 20 + (2 × 30)

v = 20 + 60

v = 80 m/s

Therefore, the final velocity of train is 80 m/s.

Answer: The correct option is C ( is very hard and burns cleanly).

Explanation:

COAL is a form of rock that is made up of mostly carbon amongst other elements which includes sulphur, nitrogen, hydrogen and oxygen. There are different types of coal which include:

--> anthracite ( 90% carbon)

--> bituminous coal ( 70-90% carbon)

--> lignite ( 60- 70% carbon) and

--> peat (60 % carbon).

Anthracite is the type of coal that contains the highest carbon content ( 90% carbon). This makes it very hard and is often a times referred to as HARD COAL. Anthracite is a higher quality coal for domestic and open fire heating. This is because it contains less impurities than other type of coal and thereby making it to BURN CLEANLY avoiding atmospheric pollution.

Answer:

0.250L of solution. 0.250 moles of solute.

Explanation:

As you can see in the image, there is a beaker with an amount of solution. 1/2L are 500mL and each line of the beaker represents 100mL. That means the volume of the solution is approximately 250mL = 0.250L

Molarity is an unit of concentration defined as the moles of solute per liter of solution. A solution that is 1.000M contains 1.000 moles of solute per liter of solution.

As the volume of the solution is 0.250L, the moles are:

0.250L * (1.000mol/L) = 0.250 moles of solute

(1) Seven electrons

1s² 2s²2p³

There are two electrons in the 2s subshell and three in the 2p subshell. The remaining two electrons are in the inner 1s subshell.

(2) 22 electrons

1s² 2s²2p⁶ 3s²3p⁶ 4s²3d²

There are two electrons in the 4s subshell and two in the 2p subshell. The remaining 18 electrons are in the inner subshells.

(3) 17 electrons

1s² 2s²2p⁶ 3s²3p⁵

There are two electrons in the 3s subshell and five in the 2p subshell. The remaining 10 electrons are in the inner subshells.

(4) n = 4, l = 2

(5) N=2 I=0 MI=0

(6) There can be two electrons in one orbital maximum. The s sublevel has just one orbital, so can contain 2 electrons max. The p sublevel has 3 orbitals, so can contain 6 electrons max. The d sublevel has 5 orbitals, so can contain 10 electrons max.

(7) n = 4 can hold up to 16 electrons

There are 4 sublevels; 42, 4p, 4d and 4f

4s (1 orbital), 4p (3 orbitals)

4d (5 orbitals), 4f (7 orbitals)

Maximum number of electrons in energy level: 16

s = 1 orbital

p = 3 orbitals

d = 5 orbitals

f = 7 orbitals

Add these up;

1 + 3 + 5 + 7 = 16

(8) 14 electrons If l = 3, the electrons are in an f subshell. The number of orbitals with a quantum number l is 2l + 1, so there are 2×3 + 1 = 7 f orbitals. Each orbital can hold two electrons, so the f subshell can hold 14 electrons.

sorry i didn't do the last two.. also sorry if some or none of these are correct, i tried my best

Answer:

-2,802.960 kJ

Explanation:

The dimensional equation of the given quantities is presented as follows;

(6 mol) × (-393.5 kJ/mol) + (6 mol) × (-285.83 kJ/mol) - (1 mol) × (-1,273.02 kJ/mol) = ? kJ

The equation, can be written as follows;

[tex]\left (6 \times (-393.5) \, mol \times \dfrac{kJ}{mol} \right ) + \left(6 \times (-285.83) \, mol \times \dfrac{kJ}{mol} \right) - \left (1 \times (-1,273.02) \, mol \times \dfrac{kJ}{mol} \right) = ?[/tex]We note that [tex]mol \times \dfrac{kJ}{mol} \right) = kJ[/tex], therefore, the above equation becomes;

[tex]\left (6 \times (-393.5) \ kJ\right ) + \left(6 \times (-285.83) \ kJ \right) - \left (1 \, \times (-1,273.02) \ kJ \right) = -2,802.960 kJ[/tex]

Answer:

C. ((6 mol)(-393.5 kJ/mol) + (6 mol)(-285.83 kJ/mol)) - (1 mol)(-1,273.02 kJ/mol)

Explanation:

Got it right on edge.
: the one after is -2803.

Answer: the answer is C

IF U MIGHT NEED AN EXPLANATION FEEL FREE TO COMMENT

The laboratory equipment like the burette, pipette, and measuring cylinders are used in process of titration process. The solution of NaOH is added by the burette. Thus, option C is correct.

Titration has been the analytical technique that uses the known and measured quantity of the solution to estimate the volume of another solution with an unknown volume and known molar concentration.

The laboratory equipment like burette, pipette, and measuring cylinders are used in measuring the volume in the titration process. The burette is filled with sodium hydroxide to measure its quantity.

The pipette is used to transfer the volume of the solution that is known (hydrochloric acid) and the measuring cylinder is used to measure the liquid (water) that is used in chemistry experiments.

Therefore, option C. pipette, burette, and measuring cylinder are the apparatus used in the titration process.

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Answer:

B.Thermal insulation minimizes energy loses to the atmosphere.

Explanation:

It is important because it helps to stop hit from transferring from the calorimeter to the environment. This would help to have an accurate measurement of the heat that was used in the chemical process. The greatest cause of error that happens in calorimetry is when heat is lost to the environment. To reduce this, you insulate the calorimeter and add a cover.

Answer:

P2 = 900 mmHg.

Explanation:

Given the following data;

Initial pressure = 450 mmHg

Initial temperature = 100°C

Final temperature = 200°C

To find the final pressure, we would use Gay Lussac's law;

Gay Lussac states that when the volume of an ideal gas is kept constant, the pressure of the gas is directly proportional to the absolute temperature of the gas.

Mathematically, Gay Lussac's law is given by;

[tex] PT = K[/tex]

[tex] \frac{P1}{T1} = \frac{P2}{T2}[/tex]

Making P2 as the subject formula, we have;

[tex] P_{2}= \frac{P1}{T1} * T_{2}[/tex]

[tex] P_{2}= \frac{450}{100} * 200 [/tex]

[tex] P_{2}= 4.5 * 200 [/tex]

Final pressure, P2 = 900 mmHg.