an emerald can be described as...

Answer:

Percent yield = 17.3%

Explanation:

The percent yield is defined as 100 times the ratio between actual yield in grams and theoretical yield in grams (123g).

Percent Yield = Actual Yield / Theoretical yield (123g) * 100

To find actual yield we need to convert the 0.209moles to grams:

Actual yield -Molar mass Al2O3: 101.96g/mol-

0.209mol * (101.96g/mol) = 21.3g

Percent yield = 21.3g / 123g * 100

Percent yield = 17.3%

Answer:

amount, pH value.

Explanation:

The buffer range is the pH range in which the buffer performs optimally, i.e., neutralizes even when a strong acid or base is introduced to it and resists any major change in its pH value.

The buffer capacity is the amount of acid or base that can be added before the pH of the buffer solution changes significantly.

Thus, the final statement becomes,

Buffer capacity is the amount of acid or base a buffer can handle before pushing the pH value outside of the buffer range.

Answer:

Amount

pH value

Buffer capacity is the amount  of acid or base a buffer can handle before pushing the pH  outside of the buffer range.

A buffer however consists of a weak acid and its conjugate base.Its major advantage is the ability to resist changes in pH when an acid or a base is added to the solution.

The human blood is also an example of a buffer solution as it is able to resist changes in pH when we eat or drink certain types of food.

An example of a buffer include acetic acid (HC₂H₃O₂) which is a weak acid and sodium acetate (NaC₂H₃O₂) which is a salt derived from that acid).

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Answer:

Collisions between gas particles are elastic; there is no net gain or loss of kinetic energy.

Explanation:

When a gas is paced in a container, the molecules of the gas have little or no intermolecular interaction between them. There is a lot of space between the molecules of the gas.

The gas molecules move at very high speed and collide with each other and with the walls of container.

The collision of these particles with each other is perfectly elastic hence the kinetic energy of the colliding gas particles do not change.

Answer:

Pharmaceutical laboratory helps in devloping and conducting research, vaccines. Various kinds of drugs and chemical substances used and are produced at a Pharmaceutical laboratory.

The pharmaceutical laboratories performs with various hazardous substances that results in exposure to various chemicals, biological substances and radiation. To avoid any injury or infection labs need to maintain all safety measures.

Spillage and relaseing chemical substances can be lethal during transportaions by safety measures for heling in for manufacturing of such therapeutic agents spillage and avoid wastage.

Maintaining good safety standards in the pharmaceuticals laboratory will help promote the health of technicians and workers which in turn will increase productivity and attain positive outcomes.

Answer:

See explanation

Explanation:

Science as a body of knowledge seeks to understand the processes that occur in nature so as to offer plausible explanations to those processes as well as redesign nature for our benefit.

Hence, science is an inquiry into nature with the aim to improve the life of the general population of the world.

Chemistry is the study of matter and the changes that matter undergoes. Chemistry lies at the very foundation of science since changes in matter is the basis for the processes that occur in nature.

Hence, chemistry plays a critical role in understanding nature as well as amending nature to improve the living condition of the world's rapidly growing population.

Answer:

Endothermic

Explanation:

Endothermic reaction is one in which the enthalpy increases. What this implies is that, it is a closed system which absorbs heat from its surroundings and thus after reaction become cooler than prior to the reaction.

In this case, the mixture of the two liquids feel colder to touch. Thus, it is an endothermic reaction from the definition earlier given.

Answer:

Electrons

Explanation:

Electrons are produced when light with enough energy is directed onto the cathode where electrons are ejected as beam towards the screen.

Answer:

218.7 mL

Explanation:

The reaction that takes place is:

First we calculate how many HCOOH moles reacted, using the given volume and concentration:

As 1 HCOOH mol reacts with 1 LiOH mol, 32.8 mmoles of LiOH are needed to react with 32.8 mmoles of HCOOH.

Finally we calculate how many mL of a 0.150 M solution would contain 32.8 mmoles:

Answer:

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Answer:

It has a negative charge and is located in orbitals around the nucleus

Explanation:

The statement describes an electron is " It has a negative charge and is located in orbitals around the nucleus."

The electron would be a subatomic particle with a negatively one elementary charge electric charge.

Protons, that have a positive charge, as well as neutrons, which have no electrical charge, make up the nucleus. Quarks were subatomic particles that make up protons but also neutrons.

Electrons were present surrounding the atom's nucleus, in contrast to protons as well as neutrons, that are contained within the nucleus at its core. Negative electrons were drawn to the positive nucleus since the electric charges of opposite polarity attract one another.

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Answer:

C₂H₆(g) + 2.5 O₂(g) ⇒ 2 CO(g) + 3 H₂O(g)

Explanation:

Let's consider the unbalanced equation in which gaseous ethane reacts with gaseous oxygen to form carbon monoxide gas and water vapor. This is an incomplete combustion reaction.

C₂H₆(g) + O₂(g) ⇒ CO(g) + H₂O(g)

We will balance it using the trial and error method.

First, we will balance C atoms by multiplying CO by 2 and H atoms by multiplying H₂O by 3.

C₂H₆(g) + O₂(g) ⇒ 2 CO(g) + 3 H₂O(g)

Then, we get the balanced equation by multiplying O₂ by 2.5.

C₂H₆(g) + 2.5 O₂(g) ⇒ 2 CO(g) + 3 H₂O(g)

Answer:

Pressure increases

Explanation:

Boyle's law states that; '' the volume of a given mass of ideal gas is inversely proportional to its pressure at constant temperature.

Hence, when the volume of a given mass of ideal gas is decreased, the molecules of the gas come closer together so they collide with each other and the walls of the container more frequently.

This implies that the pressure of the gas increases as volume decreases in accordance with Boyle's law.

Answer:

14 moles of oxygen needed to produce 12 moles of H2O.

Explanation:

We are given that balance eqaution

[tex]2C_2H_6+7O_2\rightarrow 4CO_2+6H_2O[/tex]

We have to find number of moles of O2 needed  to produce 12 moles of H2O.

From given equation

We can see that

6 moles of   H2O produced by Oxygen =7 moles

1 mole of   H2O produced by Oxygen=[tex]\frac{7}{6}[/tex]moles

12 moles of H2O produced by Oxygen=[tex]\frac{7}{6}\times 12[/tex]moles

12 moles of H2O produced by Oxygen=[tex]7\times 2[/tex]moles

12 moles of H2O produced by Oxygen=14 moles

Hence, 14 moles of oxygen needed to produce 12 moles of H2O.

The amount of oxygen required for the combustion of ethane to produce 12 moles of water is 14 moles.

The moles of oxygen produced in the reaction can be given from the stoichiometric law of the balanced chemical equation.

The balanced chemical equation for the combustion of ethane is:

[tex]\rm 2\;C_2H_6\;+\;7\;O_2\;\rightarrow\;4\;CO_2\;+\;6\;H_2O[/tex]

The 6 moles of water are produced from 7 moles of oxygen. The moles of oxygen required to produce 12 moles of water are:

[tex]\rm 6\;mol\;H_2O=7\;mol\;Oxygen\\12\;mol\;H_2O=\dfrac{7}{6}\;\times\;12\;mol\;O_2\\ 12\;mol\;H_2O=14\;mol\;O_2[/tex]

The moles of oxygen required to produce 12 moles of water are 14 moles.

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Answer:

A. The law of Multiple Proportion

Answer:

the change in the internal energy of the system is 3,752.67 J

Explanation:

Given;

initial volume of the gas, V₁ = 30.6 L

final volume of the gas, V₂ = 1.8 L

constant pressure of the gas, P = 1.8 atm

Energy released by the system, Q = 1.5 kJ = 1,500 J

Apply pressure-volume work equation, to determine the work done on the gas;

w = -PΔV

w = -P(V₂ - V₁)

w = - 1.8 atm(1.8 L - 30.6 L)

w = 51.84 L.atm

w = 51.84 L.atm x 101.325 J/L.atm

w = 5,252.67 J

The change in the internal energy of the system is calculated as;

ΔU = Q + w

Since the heat is given out, Q = - 1,500 J

ΔU = -1,500 J  +  5,252.67 J

ΔU = 3,752.67 J

Therefore, the change in the internal energy of the system is 3,752.67 J

Answer:

[tex] This\:may\: help[/tex]

Answer:

(1) Write down the chemical reaction in the form of word equation,keeping reactants on left hand side and products on right hand side.

(2) Write symbol and formula of all reactants and products in word equation. (3) Balance the equation by multiplying the symbols and formula by smallest possible figures.

Answer:

Slower

Explanation:

The reaction between alkyl halides and sodium iodide-in-acetone is an SN2 reaction. The rate of reaction depends on the concentration of the alkyl halide as well as the concentration of the sodium iodide. It is a bimolecular reaction.

This means that if the concentration of any of the reactants is halved, the rate of reaction decreases accordingly.

Therefore, if the iodide solution is half as concentrated, the reaction is observed to be slower in accordance with the rate law;

Rate = k[alkyl halide] [iodide]

Answer:

264 g/mol

Explanation:

#electrons equal #protons = 106

Plus 1 charge => m protons = 106 + 1 = 107

Mass number: 107 + 157 = 264 g/mol

Answer:

3.36 grams Al°(s)  

Explanation:

Given AlCl₃(s), determine the mass (grams) of Al°(s) produced from electrolysis of Aluminum Chloride at 10.0 amps for 1.00 hour.

AlCl₃(s) + 378.3°F (=192.4°C) => Al⁺³(l) + 3Cl⁻(l)

formula wt. Al° = 27g/mol

Faraday Constant (F°) = 96,500 amp·sec

? grams Al°(s) = 10.0amps x (1 mole e⁻/96,500amp-sec) x (1 mole Al°(s)/3 mole e⁻) x (27g Al°(s)/1 mole Al°(s)) x 3,600 sec = 3.36 grams Al°(s)

The 3.36 grams of aluminum are produced in 1 hour by the electrolysis of molten AlCl₃ when 10A current is passed.

Electrolysis is a process that uses an electrical current to break chemical compounds. The electric current is passed through the substance to bring the chemical change by gain or loss of electrons.

The electrolysis of the aluminum chloride in the molten state is represented as:

AlCl₃  →   Al³⁺    +  3Cl⁻

At cathode:   Al³⁺  +  3e⁻  →  Al (s)

Given,  the current. I = 10 A and  t = 1 hr = 3600 s

We know that the current is calculated from the equation:  I = q/t

q = I× t

q = (10A) × (3600s)

q = 36 × 10³ C

We know, 96500 C of the charge has electrons = 1 mol

36 × 10³ C of the charge has electrons  = 0.373 mol

3 moles of electrons required to produce aluminum = 1 mol

0.373 mol of electrons will produce aluminum = 0.373/3 = 0.124 mol

We know that, the mass of one mole of Al = 27g

The mass of 0.124 mol of Al = 27 × 0.124 = 3.36 g

Therefore, the aluminum produced in 1 hour by the electrolysis of molten AlCl₃ is equal to 3.36 grams.

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Answer:

0.377 J/gºC

Explanation:

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

Mass of metal (Mₘ) = 65.3 g

Initial temperature of metal (Tₘ) = 99.8 °C

Mass of water (Mᵥᵥ) = 43.7 g

Initial temperature of water (Tᵥᵥ) = 25.7 °C

Equilibrium temperature (Tₑ) = 34.5 °C

Specific heat capacity of water (Cᵥᵥ) = 4.18 J/gºC

Specific heat capacity of metal (Cₘ) =?

The specific heat capacity of metal can be obtained as illustrated below:

Heat lost by metal = heat gained by water.

MₘCₘ(Tₘ – Tₑ) = MᵥᵥCᵥᵥ(Tₑ – Cᵥᵥ)

65.3 × Cₘ (99.8 – 34.5) = 43.7 × 4.18 (34.5 – 25.7)

65.3Cₘ × 65.3 = 182.666 × 8.8

4264.09Cₘ = 1607.4608

Divide both side by 4264.09

Cₘ = 1607.4608 / 4264.09

Cₘ = 0.377 J/gºC

Therefore the specific heat capacity of the metal is 0.377 J/gºC

Answer:

D

Explanation:

The longer handles distribute the force across a longer distance.

Answer:

less than 5 centimeters because it is a nonvascular plant

Explanation:

Mosses are a group of plants under the division Bryophyta. They are said to be the most primitive plant life in existence as they lack true roots, stems and leaves. They also lack vascular system, hence, they are regarded as non-vascular plants. They usually grow in very small sizes (about 0.2 - 10cm).

According to this question, Penny bought a club moss plant for her water garden and needs to know how tall the plant will grow so she know how much space it will need. Since it is a miss plant that lacks vascular tissues i.e. nonvascular, it will likely grow less than 5 centimeters in height.

Answer:

d

Explanation:

Answer: There are 0.0556 moles present in 44.1 mL of a 1.26 M HCl solution.

Explanation:

Given: Volume = 44.1 mL (1 mL = 0.001 L) = 0.0441 L

Molarity = 1.26 M

Molarity is the number of moles of a substance present in liter of a solution.

Therefore, moles of HCl are calculated as follows.

[tex]Moles = \frac{moles}{Volume (in L)}\\1.26 M = \frac{moles}{0.0441 L}\\moles = 0.0556 mol[/tex]

Thus, we can conclude that there are 0.0556 moles present in 44.1 mL of a 1.26 M HCl solution.

Answer:

I expect to observe a change in colour from reddish brown to a colourless solution

Explanation:

Bromine (Br2) attacks the electron rich carbon-carbon triple bond in but-2-yne, an alkyne to form an initial product 2, 3 dibromobut-2-ene; which reacts with excess bromine to form a final product 2,2,3,3 -tetrabromobutane.

The reaction occurs in two steps. On approaching but-2-yne, bromine molecule becomes polarised forming an induced dipole containing a bromonium ion.

Br - Br → Br+ - Br-

The bromonium ion (Br+) formed then attacks the carbon - carbon triple bond to form the initial product

2,3- dibromobut-2-ene

CH2-C≡C-CH2 + Br+ →

CH2 - CBr =CBr-CH2

(2,3- dibromobut-2-ene)

Which in the presence of excess bromine gives the final product

2,2,3,3 - tetrabromobutane.

CH2 - CBr =CBr-CH2 + Br2 →

CH3 -CBr2-CBr2 - CH3

2,2,3,3 - tetrabromobutane.

A visible change in colour from the reddish-brown colour of Bromine to a colourless solution is observed during the reaction.

Answer: When excited sodium atoms may emit radiation having a wavelength of 589nm. It's wavelength in meters is [tex]589 \times 10^{-9} m[/tex].

Explanation:

Given: Wavelength = 589 nm

It is known that,

[tex]1 nm = 10^{-9} m[/tex]

Hence, 589 nm is converted into meters as follows.

[tex]589 nm = 589 nm \times \frac{10^{-9}m}{1 nm}\\= 589 \times 10^{-9} m[/tex]

Thus, we can conclude that when excited sodium atoms may emit radiation having a wavelength of 589nm. It's wavelength in meters is [tex]589 \times 10^{-9} m[/tex].

Answer:

0.043 M

Explanation:

The reaction that takes place is:

First we calculate how many HCl moles reacted, using the given concentration and volume required to reach the equivalence point:

As 1 mol of H⁺ reacts with 1 mol of OH⁻, in the 25.0 mL of the Ca(OH)₂ sample there are 1.0817 mmoles of OH⁻.

With that in mind we can calculate the hydroxide ion concentration in the original sample solution, using the calculated number of moles and given volume:

The titration is termed the neutralization reaction with the acid and base. The concentration of hydroxide in the titration is 0.0865 M.

The neutralization reaction is given as the reaction in which the acid and base react to form the salt and water, stabilizing the pH of the solution.

The neutralization of acid and base to identify the strength can be given as:

[tex]\rm M_V_1=M_2V_2[/tex]

Substituting the strength and the volume of calcium hydroxide and the HCl with the volume:

[tex]\rm 0.029\;M\;\times\;37.3\;mL=M_2\;\times\;25\;mL\\M_2=\dfrac{ 0.029\;M\;\times\;37.3\;mL}{25\;mL} \\M_2=0.0432\;M[/tex]

The strength of the calcium hydroxide in the reaction is 0.04326 M.

One molar unit of calcium hydroxide results in 2 molar units of hydroxide. The molar unit of hydroxide in 0.04326 M calcium hydroxide is:

[tex]\rm 1\;M\;Ca(OH)_2=2\;M\;OH^-\\\\0.04326\;M\;Ca(OH)_2=0.04326\;\times\;2\;M\;OH^-\\0.04326\;M\;Ca(OH)_2=0.0865\;M\;OH^-[/tex]

The concentration of hydroxide ion in the titration is 0.0865 M.

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The various factors that impact the solubility of substances in water are - nature of solute and solvent, temperature, pressure and pH.

The solubility of substances in water is influenced by several factors:

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