Select all of the following that are combustion reactions.

According to stoichiometry and balanced chemical equation  10 moles of lithium metal react to yield 5.00 mole of hydrogen gas.

Stoichiometry is the determination of proportions of elements or compounds in a chemical reaction. The related relations are based on law of conservation of mass and law of combining weights and volumes.

Stoichiometry is used in quantitative analysis for measuring concentrations of substances present in the sample.

In the  balanced chemical equation as 2 moles of lithium produce 1 mole of hydrogen.

∴for 5 moles of hydrogen to be liberated,5×2/1=10 moles of lithium are required.

Thus, 10 moles of lithium are required to react to yield 5 moles of hydrogen gas.

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Answer:

ethyl ethanoate

Explanation:

it helps you

Answer:

a

Explanation:

bc i think it is and pls i wany to have ajebehhe

Answer:

if it burns

Explanation:

The percentage composition of oxygen (O) in the compound, given that it contains 19.76 g of O is 39.52%

The percentage composition of substance in a compound can be obtained by using the following formula:

Percentage = (mass of substance / mass of compound) × 100

Using the above formula, we can determine the percentage composition of the oxygen (O) as illustrated below:

Percentage = (mass of solute / mass of solution) × 100

Percentage of O = (19.76 / 50.0) × 100

Percentage of O = 39.52%

Thus, we can conclude that the percentage composition of the O is 39.52%

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The test variable (independent variable) in Omar's experiment is the masses of the model rockets; option D.

Variables in an experiment refer to those measurements or factors that are under the control of the researcher and which can be altered by the researcher in order to study the effect of changes on the study.

The three types of variables in a study are:

In the study conducted by Omar, the test variable (independent variable) is the time of rocket stays up in the air.

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Answer:

A

Explanation:

Fluorine is a REACTIVE nonflammable gas or liquid which will enhance combustion of other materials.

Answer:

What is the pH of an aqueous solution with a hydrogen ion concentration of [H+]=7.7×10−4 M?

The pH of an aqueous solution with a hydrogen ion concentration of [H+]=7.7×10−4 M is 3.11.

According to the Lewis structures, SF₂ is unstable as it has 2 lone pairs of electrons.

Lewis  structures are also called as electron dot structures and can be drawn if the molecular formula of a compound is known. It provides information regarding the nature of bond and the position of atoms .

They are also capable of exhibiting the lone pair if any present in a molecule or compound.Lewis defined a base to be an electron pair donor and an acid to be an electron pair acceptor.

They are capable of reflecting electronic structure of elements and even the pairing of electrons . In the diagram, each dot represents an electron while a pair of dots represent a bond between the atoms.

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Answer:

Suppose you are standardizing a sodium hydroxide solution with KHP

(molar mass=204.2 g/mol) according to the equation

KHP+NaOH⟶H2O+NaKP

You prepare the standard solution from 0.303 g of KHP

in 250.0 mL of water. You then require 9.51 mL of NaOH

solution to complete the titration.

What is the concentration of the NaOH

solution?

Answer:

The concentration of the NaOH solution can be calculated using the following equation:

Concentration (M) = (Moles of KHP/Volume of NaOH solution) x (Molar mass of KHP/1000)

Concentration (M) = (0.303 g/9.51 mL) x (204.2 g/mol/1000)

Concentration (M) = 0.064 M

The enthalpy of reaction for the formation of sulfur tetrafluoride monoxide is 16 kJ/mol.

The enthalpy of a reaction measures the sum total of the heat that is absorbed or liberated in a given reaction when reactants react to form products.

The enthalpy change of a reaction can be calculated using the formula given below:

The equation of the given reaction is as follows:

SF₄ + ¹/₂ O₂-----> SF₄O

Enthalpy of reaction = (4 * S-F + S-O) - (4 * S-F + ¹/₂ * O-O)

Enthalpy of reaction = (4 * 310 + 265) -  (4 * 310 + /₂ * 498)

Enthalpy of reaction = 16 kJ/mol

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As per the standard data, the heat evolved during one mole of calcium carbonate decomposes is 177.8 KJ. Thus 15 g or 0.15 moles of calcium carbonate when decomposed will produce 26.67 KJ of heat.

Reaction enthalpy of a substance is the heat evolved or absorbed during a reaction. Reaction enthalpy is negative for an exothermic reaction and positive for an endothermic reaction.

Molar mass of calcium carbonate = 100 g.

no.of moles in 15 g = 15 /100 = 0.15 moles.

One mole or 100 g of calcium carbonate decompose to evolve 177.8 KJ according to the scientific record.

Thus, heat evolved by the decomposition of 0.15 moles is 0.15 × 177.8 KJ = 26.67 KJ.

Hence, the heat evolved during the decomposition of 15 g of calcium carbonate is 26.67 KJ.

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Answer:

GL

Explanation:

Elements that are chemically similar to calcium (Ca) can interfere with bodily functions are Beryllium and magnesium.

The chemical element calcium has the atomic number 20 and the letter Ca as its symbol. Calcium is an alkaline earth metal that reacts with air to create a black oxide-nitride coating. Its heavier homologues barium and strontium are most similar to it in terms of physical and chemical characteristics.

Calcium reacts when heated with boron, carbon, sulfur, phosphorus, halogens, and hydrogen. Calcium is more expensive and less reactive than sodium, despite being a better reducing agent than the latter.

Thus, Elements that are chemically similar to calcium (Ca) can interfere with bodily functions are Beryllium and magnesium.

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Answer:

Molar mass of dye = 225.8 g/mol

Mass of dye = 17.26 mg

Volume of stock solution = 500.0 mL

Concentration of dye (M) = (17.26 mg/225.8 g/mol) / (500.0 mL/1000 L) = 0.000769 M

Concentration of dye (mM) = 0.769 mM

According to the molar concentration, the concentration of the dye in the stock solution is 15.04×10⁻³M and 15.04×10⁻⁶mM.

Molar concentration is defined as a measure by which concentration of chemical substances present in a solution are determined. It is defined in particular reference to solute concentration in a solution . Most commonly used unit for molar concentration is moles/liter.

The molar concentration depends on change in volume of the solution which is mainly due to thermal expansion. Molar concentration is calculated by the formula, molar concentration=mass/ molar mass ×1/volume of solution in liters.

In terms of moles, it's formula is given as molar concentration= number of moles /volume of solution in liters.

Substitution of values in formula gives, M= 0.017/225.8×1/0.5=15.04×10⁻³ M or 15.04×10⁻⁶ mM.

Thus, the concentration of the dye in the stock solution is 15.04×10⁻³M and 15.04×10⁻⁶mM.

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As you can see the picture, in the three given compounds i.e. ethane, ethene and ethyne, ethyne have shortest bond. Bond length of ethyne is very short when compared to the ethane and ethene. Shorter the bond, bond strength will be more. Hence, our answer is ethyne.

Answer:

ethyne has shortest bond

Answer:The pressure exerted by the gas is 100kPa

Explanation:Let's apply the Charles Gay Lussac law, to solve the question.

At constant volume, the pressure varies proportionally with the temperature.

P initial / T° initial = P final / T° final

50kPa / 20°C = P final / 40°C

Temperature has increased the double, so the pressure will be increased, the double too.

100 kPa

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The volume of the sample in milliliters is 1.0 ml and number of moles of gold dissolved in 1 ml of sea water is 2.5×10[tex]^-14[/tex] moles  which is mentioned in the question and 1 mole of substance has 6.023×10²³ particles.

Mole is defined as the unit of amount of substance . It is the quantity measure of amount of substance of how many elementary particles are present in a given substance.

It is defined as exactly 6.022×10²³ elementary entities. The elementary entity can be a molecule, atom ion depending on the type of substance. Amount of elementary entities in a mole is called as Avogadro's number.

It is widely used in chemistry as a suitable way for expressing amounts of reactants and products.For the practical purposes, mass of one mole of compound in grams is approximately equal to mass of one molecule of compound measured in Daltons. Molar mass has units of gram per mole . In case of molecules, where molar mass  in grams present in one mole  of atoms is its atomic mass.

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Answer:

[tex] \huge{ \bold{ \text{8.31 moles}}}[/tex]

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

[tex] \bold{n= \frac{N}{L}}\\ [/tex]

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question

N = 5.0 × 10²⁴ [tex] K_2SO_4 \: \text{formula units} [/tex]

[tex] \: n = \frac{5 \times {10}^{24} }{6.02 \times {10}^{23} } \\ = 8.3056[/tex]

We have the final answer as

She found out that the gypsum block with the water balloon cracked while the other block did not.The water in the balloon freezes and expands, just like the water in the cracks of rocks - is this similar to the weathering of rocks by ice.

Gypsum is a soft sulfate mineral that is made up of calcium sulfate dihydrate and has the chemical formula CaSO₄ . 2H₂O. It is extensively mined, and used as fertilizer, the primary ingredient in many types of plaster, sidewalk or blackboard chalk, and drywall, and it is also widely utilized as a building material.

In nature, water flows from small rivers and occasionally through fissures in the rocks or terrain, and when it freezes, it puts too much pressure on the rock, causing it to split. The similarity in Jades' test is that the water balloon has water when it is placed in the gypsum, and when she adds a cold environment, the ice within the water balloon freezes and expands, putting too much pressure on the rock, causing it to shatter.

Ice Wedging is a example of this.

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Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, there are 8.41×10⁻¹⁸moles of oxygen in 5.07x10⁶atoms of oxygen.

The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity of amount of substance.

Given number of atoms= 5.07x10⁶atoms

we know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number.

mole =given number of atoms ÷ 6.022×10²³(Avogadro number)

Substituting the values

mole of oxygen=5.07x10⁶÷ 6.022×10²³

mole of oxygen =8.41×10⁻¹⁸

Therefore, there are 8.41×10⁻¹⁸moles of oxygen in 5.07x10⁶atoms of oxygen.

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The wavelength is same.

What is wavelength?

Wavelength can be defined as the distance between two successive by throughs of a wave.

The question wants you to determine the energy that is the incoming photon by the  must have in order to the accept the electron that melted  it tob the jump to 2 to 1.

A good starting point here will be to calculate the energy of to the photon emitted when the electron falls from  1 to 2

by applying the Rydberg equation.

1/π = R

λ

 si the wavelength of the emittted photon R

 is the Rydberg constant, equal to 1.907.

This means that you haveλ=

4.10

So, you know that when an electron falls from the

to  

a photon of wavelength by the

410 nm

 is emitted. This implies by  that in order to the for the electron by jump to  the 2 to 1 .

 it must absorb a photon of the same wavelength.

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The partial pressure of oxygen is the product of its mole fraction and the total pressure. Partial pressure of O₂ here, is 0.82 atm.

Partial pressure of an individual gas in a mixture of gases is its contribution to the total pressure of the gas mixture. According to Dalton's law of partial pressures, the total pressure of the mixture is the sum of partial pressures of the individual gases.

The partial pressure of the individual gases will be the product of the mole fraction and total pressure.

mass of oxygen = 16 g/mol

number of moles in 50 g = 50 /16 = 3.125 moles.

mass of neon = 20 g/mol

moles in 50 g =  50 / 20 = 2.5 moles.

Mole fraction of oxygen =  3.125/ (3.125 + 2.5) = 0.55.

Partial pressure = mole fraction × total pressure

                           = 0.55 × 1.50 atm = 0.82 atm.

Therefore, the partial pressure of O₂ in the mixture is 0.82 atm.

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The standard enthalpy change for the reaction 2A + B ⇌ 2C + 2D   is 195 kJ/mol.

The enthalpy of a reaction is a measure of the heat changes that occur when reactants form a product in a given reaction.

The enthalpy change of a reaction can be calculated using the formula given below:

Enthalpy of reaction = sum of enthalpies of the products  - sum of enthalpies of the reactants

Considering the given reaction: 2A + B ⇌ 2C + 2D  

Enthalpy of reaction = (2 * C + 2 * D) - (2 * A + B)

Enthalpy of reaction = {[2 * 177 + 2 * (-515)] - [2 * (-231) + (-409)]}

Enthalpy of reaction = 195 kJ/mol

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Answer:

I got it right on Pluto

Explanation:

You are pretty much just taking away 2 of the hydrogen

Answer:

3 grams C₅H₁₀O₅

Explanation:

To find the mass of ribose needed to prepare the sample, you need to

(1) convert the volume from mL to L (1,000 mL = 1 L)

(2) calculate the number of moles (M = moles / L)

(3) convert moles to grams (using the molar mass of ribose)

The molecular formula of ribose is C₅H₁₀O₅. It is important to arrange all of the ratios/conversions in a way that allows for the cancellation of units.

(Step 1)

 200 mL C₅H₁₀O₅                   1 L
----------------------------  x  ----------------------  =  0.2 L C₅H₁₀O₅
                                           1,000 mL

(Step 2)

Molarity (M) = moles / volume (L)                 <----- Molarity ratio

0.1 M = moles / 0.2 L                                     <----- Insert values

0.02 = moles                                                  <----- Multiply both sides by 0.2 L

(Step 3)

Atomic Mass (C): 12.011 g/mol

Atomic Mass (H): 1.008 g/mol

Atomic Mass (O): 15.999 g/mol

Molar Mass (C₅H₁₀O₅): 5(12.011 g/mol) + 10(1.008 g/mol) + 5(15.999 g/mol) = 150.13 g/mol

 0.02 moles C₅H₁₀O₅              150.13 g
----------------------------------  x  -------------------  =  3 grams C₅H₁₀O₅
                                                  1 mole

Answer:

KE=1\2mv2

KE=0.5 *0.15*(36)2

97.2j

Answer:

Explanation:

1. No, I simply would not feel safe.

2. Power plant manager

3. exposure to chemicals

To solve such this we must know the concept of displacement reaction. Therefore, the correct option is option C that is displacement reaction.

Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved. There are so many types of chemical reaction reaction like combination reaction, double displacement reaction.

when zinc reacts with copper oxide then zinc displace copper from copper oxide as zinc is more reactive than copper on the reactivity series. So, copper is displaced by zinc.

Therefore, the correct option is option C that is displacement reaction.

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Answer: 0.295g

Explanation: The answer is 0.295g. Normally you would start by checking which of your reactants is the limiting reactant, but since you have excess HCl, you don't need to worry about that. Start by converting grams of iron to moles (done by dividing grams by iron's molar mass).

Next, you convert moles Fe to moles H2 by checking the coefficients in front of Iron and H2. Divide by iron's coefficient and multiply by H2's

Finally, you multiply by the molar mass of H2. To find it, multiply the molar mass of hydrogen by 2.

Easy way to read it:
5.45/44.845 x 3/2 x 2(1.008) = 0.295