dry cleaners use tetrachloroethylene (C2CL4) to dissolve oil and grease because C2CL4 is

If you only have the percent composition of each element in a give compound, you can't determine yet the empirical formular for the compound. The problem is, the percent composition only gives relative numbers for each element. What can be determined is the empirical stochiometry of one element relative to the others.

For example, supose you have a compound with element X and Y, with the percent composition you can determine how much X you have relative to how much Y you have. Say you determine that for each 2 X you have 3 Y, the formula can be X₂Y₃ but it can also be X₄Y₆ or even othre possibilities.

To determine the empirical formula you need to know how many of one of the elements you have in each compound. A common way of getting the empirical formula is to use the percent composition and, in addition, the molar mass of the compound, which will make it possible to get the empirical formula from the relative ratios of each element you have.

Electronegativity is defined as the ability of an element to accept electrons to its shell during a chemical reaction for the formation of a stable bond structure.

A neutral atom is the atom that contains an equal amount of electrons and protons which means that is has a zero net charge. Example is sodium.

Electronegativity is defined as the ability of an element to accept electrons to its shell during a chemical reaction for the formation of a stable bond structure.

During ionic bond formation, the elements involved tries to obtain an octet structure by either donating or accepting electrons.

Alkali metals( such as the neutral element of sodium? have the lowest electronegativities, while halogens have the highest.

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We have a neutralization between the HCl (acid) and Ba(OH)2 (base):

To calculate the mL asked, we need to use the next formula:

M1 x V1 = M2 x V2 (1)

We assign number 1 to HCl and number 2 to Ba(OH)2

Remember: M molarity and V volume

-----------------

Data:

We know M1 = 0.165 M (HCl) and M2 = 0.101 M, V2 = 25.0 mL.

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Procedure:

We clear V1 from (1):

V1 = M2 x V2/M1 = 0.101 M x 25.0 mL/0.165 M = 15.3 mL

Answer: V1 = 15.3 mL

Answer:

Chlorine and Bromine are also halogens so they are similar to fluorine

Explanation

There are said to have two different conditions of a gas.

First condition is STP which means: pressure = 1 atm and temperature (absolute) = 0 °C + 273 = 273 K

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It is said that the temperature remains constant, therefore we can apply Boyle's law which states that the pressure of a gas tends to decrease as the volume of the container increases.

Water molecules that have escaped or evaporated from the body of water then water get excited and they begin to gain kinetic energy

A water molecule has a three atom two hydrogen and one oxygen atom and that's why water is sometime refred to as H₂O and a single drop of water contain billion drop of molecule and evaporation is the process in which given to the change that occurs to a substance that changes it from its liquid state to a gaseous state

When water get evaporates the molecule of water in a glass will get excited and they begin to gain kinetic energy and vigorously hit the wall of glass

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Answer:

Percent yield = 27.3%.

Explanation:

First, let's write the chemical equation:

The limiting reactant, in this case, would be O2 because we have an excess of ZnS. So, we have to convert 42.5 g of O2 to moles. Remember that the molar mass of O2 is 32 g/mol (you can calculate the molar mass of a compound using the periodic table). The conversion will be:

With this value, we're going to find the number of moles of SO2 produced by 1.33 moles of O2. You can see in the chemical equation that 3 moles of O2 reacted produces 2 moles of SO2, so the calculation would look like this:

The next step is to find the mass of SO2 based on its number of moles and the molar mass of SO2 which is 64 g/mol, like this:

And finally, we replace the values that we have in the formula of percent yield:

Our experimental yield is the mass that we obtained of SO2 which is 15.5 g and the theoretical yield is the mass that we found through stoichiometry which is 56.8g:

The percent yield of this reaction would be 27.3%

When drawing an electron dot diagram, you need to check the exact number of electrons that an atom has in its shell, only the valence electrons must be drawn

Answer

A. X-rays

Explanation

There are seven regions in the electromagnetic spectrum (EM) which in order of lowest to highest frequency are:

Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

Therefore, of the following EM waves given in the options, the one that has the highest frequency is A. X-rays

Answer:

C

Explanation:

Because the suspect touched something at the crime scene and thus he's fingerprint are matching

It is to be noted that Coibacin B has three Chiral Centers. A chiral center is a molecule atom that is bound to four separate chemical species, permitting optical isomerism.

Coibacin B is a natural substance with a substantial anti-inflammatory effect and possible utility in the treatment of leishmaniasis, a parasitic illness.

It should be noted that Leishmaniasis is a parasite infection that may be found in the tropics, subtropics, and southern Europe. It is considered a neglected tropical illness (NTD).

Infection with Leishmania parasites, which are disseminated by the bite of phlebotomine sand flies, causes leishmaniasis.

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To answer this question we have to compare the specific heats of each substance.

The specific heat of a substance is the amount of energy required to make 1 gram of a substance increase its temperature by 1 °C. The greater the specific heat of a substance the more energy it will be required to heat it up.

The specific heat of water is 4.18J/g°C and the specific heat of aluminum is 0.897J/g°C.

It means that the amount of energy required to heat water is greater than the one to heat aluminum.

It means that the answer is TRUE.

0.2 grams

The balanced reaction between zinc and hydrochloric acid is given as:

Given the following parameters

Mass of Zinc = 6.5grams

Determine the mole of Zinc

Mole of Zn = mass/molar mass

Mole of Zn = 6.5/65.38

Mole of Zn = 0.0994moles

According to stoichiometry, 1 mole of Zinc produced 1 mole of hydrogen gas, hence the mole of hydrogen gas required will be 0.0994moles

Determine the mass of hydrogen gas produced

Hence the mass of hydrogen that were released is 0.2 grams

Since both metals are in the same group in the periodic table and both non-metals are also in the same group in the periodic table, they have the same charge (metals = 1+; non-metals = 1-). So this makes the reaction easier for us:

NaCl + LiBr = LiCl + NaBr

Answer:

Hydrogen bonding is a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom.

Explanation:

The polarity of a molecule is given by the difference in charges, hydrogen has a slightly positive charge and oxygen has a negative charge. Its electronegativity difference between hydrogen and oxygen is less than 1.7 making the bond a covalent bond.

That said, we can rule out options A and D. Now, the state of matter does not affect the polarity of the molecule, so option B will also be incorrect.

The correct option will be C, since there is a difference in charges that makes water polar.

Answer: C) The uneven bend in the bond between oxygen and hydrogen

Explanation:

First, let's write the balanced equation of formation of MgCl2 from Mg and Cl2:

Mg + Cl2 → MgCl2

Now let's transform 10.0g of Mg into moles, using the following formula: moles = mass/molar mass

molar mass of Mg = 24.3 g/mol

moles = 10/24.3

moles = 0.412 moles

Now we use the equation ratio between Mg and MgCl2 to find the quantity of MgCl2 in moles.

1 mole of Mg produces 1 mole of MgCl2.

So 0.412 moles of Mg produces 0.412 moles of MgCl2.

Now we transform 0.412 moles of MgCl2 into mass using the following formula: mass = moles x molar mass

Molar mass of MgCl2: 24.3 + (2*35.45) = 95.21 g/mol

Mass = 0.412 * 95.21

Mass = 39.2 g

Answer: The theoretical yield of MgCl2 is 39.2 g.

Answer:

2.95 L

Explanation:

To find the new volume, you need to use the Charles' Law equation:

V₁ / T₁ = V₂ / T₂

In this equation, "V₁" and  "T₁" represent the initial volume and temperature. "V₂" and "T₂" represent the final volume and temperature. Since you want your final volume in liters, you first need to convert 3,500 mL to L. Then, you need to convert the temperatures from Celsius to Kelvin. Finally, you can plug the given values into the equation and simplify to find "V₂".

V₁ = 3,500 mL / 1,000 = 3.5 L               V₂ = ? L

T₁ = 80°C + 273 = 353 K                         T₂ = 25°C + 273 = 298 K

V₁ / T₁ = V₂ / T₂                                      <----- Charles' Law equation

(3.5 L) / (353 K) = V₂ / (25°C)                <----- Insert values

0.00992 = V₂ / (298 K)                         <----- Divide left side

2.95 = V₂                                               <----- Multiply both sides by 298 K

1) Chemical equation

2) Moles of CO2 produced oxygen reacts

The molar ratio

2 mol O2: 1 mol CO2

If 36 mol O2 reacts, it will produce 18 mol CO2.

.

The question requires us to calculate the number of moles of each element (magnesium, chlorine and oxygen) in 8.30 moles of the compound magnesium perchlorate (Mg(ClO4)2).

From the molecular formula of magnesium perchlorate we can take the following information:

- in 1 mol of Mg(ClO4)2, there is only 1 mol of Mg;

- in 1 mol of Mg(ClO4)2, there are 2 moles of Cl;

- in 1 mol of Mg(ClO4)2, there are 8 moles of O.

With the information above, and knowing that the amount of Mg(ClO4)2 given by the question was 8.30 moles, we can calculate the amount, in moles, of each element:

1 mol Mg(ClO4)2 --------------- 1 mol Mg

8.30 mol Mg(ClO4)2 ---------- x = 8.30 mol Mg

1 mol Mg(ClO4)2 --------------- 2 mol Cl

8.30 mol Mg(ClO4)2 ---------- y = 2 x 8.30 mol Cl = 16.6 mol Cl

1 mol Mg(ClO4)2 --------------- 8 mol O

8.30 mol Mg(ClO4)2 ---------- z = 8 x 8.30 mol O = 66.4 mol O

Therefore, there are 8.30, 16.6 and 66.4 moles of Mg, Cl and O in 8.30 moles of magnesium perssufate.

Answer: a

explanation: Make a ratio of the number of moles and do the calculations. Do you get it?

The volume of a gas that has a pressure of 1.25 atm at 22℃ is 96.88L.

The volume of a gas can be calculated by using the following formula:

PV = nRT

Where;

According to this question, 5.00 mole sample of oxygen gas has a pressure of 1.25 atm at 22℃. The volume can be calculated as follows:

1.25 × V = 5 × 0.0821 × 295

1.25V = 121.0975

V = 96.88L

Therefore, 96.88L is the volume of the gas

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In this question, we have to find the limiting reactant based on the following reaction:

CHCl3 + Cl2 -> CCl4 + HCl

We have:

25 grams of CHCl3

25 grams of Cl2

The molar ratio between these two compounds is 1:1, 1 mol of CHCl3 for 1 mol of Cl2

Now we have to find the number of moles of each reactant, let's start with CHCl3, we will use its molar mass, 119.38g/mol:

119.38g = 1 mol

25g = x moles

119.38x = 25

x = 25/119.38

x = 0.209 moles of CHCl3

According to the molar ratio, if we have 0.209 moles of CHCl3, we will also have 0.209 moles of Cl2, which has a molar mass of 70.9g/mol

Let's find the mass of 0.209 moles of Cl2:

70.9g = 1 mol

x grams = 0.209 moles of Cl2

x = 14.81 grams

We only need 14.81 grams of Cl2 to react with 25 grams of CHCl3, since we have more Cl2 than we actually need, this makes Cl2 the excess reactant, and CHCl3 will be the limiting reactant. Letter C

Answer:

Explanation:Consider the balanced thermochemical equation given below: AH = -125.9 kJ W(s) + 3 H2O(g) WO3(s) + 3 H2(g) If a mass of 94.6 g H2 is produced, what is the enthalpy change? Express your answer in kJ. Express your answer to the correct number of significant figure, in scientific notation and include the unit with

To answer this question, we have to use the dilution rule, that is represented by the following equation:

Where C1 and C2 are the initial and final concentrations and V1 and V2 are the initial and final volumes.

Solve the equation for V2 to find the final volume:

The final volume of the solutions has to be 195mL. Since we already have 65mL, we need to add 130mL of water to have 195mL in total.

It means that the correct answer is 130mL.

Molarity or molar concentration is a measure of the concentration of a chemical species, of a solute in a solution, using as units, number of moles, and volume in liters. The formula for Molarity is:

M = n/V

Where:

n = number of moles

V = volume in Liters, 1 Liter

But we need to find the number of moles, we will do so by using its molar mass, KI = 166g/mol and the given mass in the question, 500g grams

166g = 1 mol

500g = x moles

x = 3.012 moles

Now we can use the Molarity formula

M = 3.012/1

M = 3.012 M, this is the molar concentration of the solution, 2

For each particle (molecule) of Ca(OH)2 that was present, assuming full dissociation of the complex, you would get two particles (ions). CaO + H2O equals Ca(OH)2 (2 particles)

A 0.561 M solution contains 0.561 moles of Ca(OH)2 per kilogram of solvent. Ions' molality would be 2 x 0.561m = 1.122m.

The most used unit for expressing solution concentration is molarity (M), which is calculated by dividing the solute concentration in moles by the volume of the solution in liters: M stands for moles of solute per liter of solution.

The kilograms of solvent divided by the moles of ions in the solution is the molality. As an illustration, if You will have 1.0 molal concentration of sodium chloride, for instance, if 1.0 moles of sodium chloride are dissolved in 1.0 kilogram of solution.

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Answer:

The Arrhenius acids in the list are:

HCl, HBr , H2SO4 , H3PO4 , HNO3 , HF

The Arrhenius bases are:

NaOH , NH4OH , LiOH , Ba(OH)2 , CsOH and KOH

Explanation:

An Arrhenius acid increases the concentration of H+ ions while an Arrhenius acid increases the concentration of OH- ions

Thus, an Arrhenius acid would yield H+ ions on ionization while an Arrhenius base will yield OH- ions on ionization

The Arrhenius acids in the list are:

HCl, HBr , H2SO4 , H3PO4 , HNO3 , HF

The Arrhenius bases are:

NaOH , NH4OH , LiOH , Ba(OH)2 , CsOH and KOH

According to the explanation about oxidizing and reducing agents from the previous session, we will find the answers to this question as well

Oxidation numbers are mostly found in previously made tables, there are plenty of tables where you can see the oxidation numbers for almost every element, a few rules to have in mind is H is usually +1, O is -2, Halogens are -1, group 1A metals are +1, transition metals are the ones that will shift a lot

1. Sn + 2 HCl -> SnCl2 + H2, this is the properly balanced equation

REACTANTS

Sn = 0, since it's a lone element in the reaction we assume its charge is 0 because is stable

H = +1

Cl = -1, it's a halogen

PRODUCTS

Sn = +2, we see now that Sn was oxidized and now has a positive charge

Cl = still -1

H2 = 0, was reduced, now with a 0 charge

2. 2 NaBr + Cl2 -> 2 NaCl + Br2

REACTANTS

Na = +1, metal from group 1A

Br = -1, halogen

Cl2 = 0 stable element

PRODUCTS

Na = +1

Cl = -1, it will be reduced

Br = 0, it will be oxidized

3. SiCl4 + 2 Mg -> 2 MgCl2 + Si

REACTANTS

Si = +4

Cl = -1

Mg = 0

PRODUCTS

Mg = +2, it will be oxidized

Cl = -1

Si = 0, it will be reduced

A ionic compound is made of two ions, one with positive charge and the other one with a negative charge.

The ion with positive charge is known as cation and the one with negative charge is known a anion.

It means that the correct answer is A. A positive cation and a negative anion.