What is the AHsol for LiF → Lit + F-? The lattice energy is -1,036 kJ/
mol, the enthalpy of hydration for Lit is -499
kJ/mol, and the enthalpy of hydration for F-is-431 kJ/mol. Use A Hooi = -A Hat + AHhydr.
0-968 kJ/mol
-106 kJ/mol
106 kJ/mol
1,966 kJ/
mol

Answer:

17

Explanation:

i need points

Answer:

The composition of air can be determined by an experiment which includes passing a known volume of air, measured at a known temperature and pressure, over sufficient amount heated copper granules/powder, and measuring the volume gas remaining after the gas cools down to the temperature at which the first measurement was taken

Oxygen reacts with copper according to the following chemical reaction

2Cu (s) + O₂ (g) → 2CuO (s)

Cupper does not react with the other constituents of air

Whereby the initial volume of air was 100 cm³, we have;

Percentage of oxygen in air = 100 - The final volume reading of the container initially holding the air

When done using am appropriate experimental setup, the percentage of gases remaining equals 79% to 80%, therefore, the percentage composition of oxygen in air is between 20 and 21 percent

Explanation:

Answer:

1.717

Explanation:

Answer:

Neutron, neutral subatomic particle that is a constituent of every atomic nucleus except ordinary hydrogen. It has no electric charge and a rest mass equal to 1.67493 × 10−27 kg—marginally greater than that of the proton but nearly 1,839 times greater than that of the electron.

Answer:

Explanation:

NCO 2= 4,5

VCO2=  4,5* 22,4=100,8

A. 0.038 g.

Explanation:

The decay of carbon-14 is a first order reaction.

The rate constant of the reaction (k) in a first order reaction = ln (2)/half-life = 0.693/(5730 year) = 1.21 x 10⁻⁴ year⁻¹.

The integration law of a first order reaction is:

kt = ln [Ao]/[A]

k is the rate constant = 1.21 x 10⁻⁴ year⁻¹.

t is the time = 17,190 years.

[Ao] is the initial concentration of carbon-14 = 0.300 g.

[A] is the remaining concentration of carbon-14 = ??? g.

∵ kt = ln [Ao]/[A]

∴ (1.21 x 10⁻⁴ year⁻¹)(17,190 years) = ln (0.300 g)/[A]

2.08 = ln (0.300 g)/[A]

Taking exponential for both sides:

8.0 = (0.300 g)/[A]

∴ [A] = 0.0375 g ≅ 0.038 g

Answer:

The lighting filters use subtractive properties to bring light of a color to the eye because subtractive color mixing uses white light source with a series of filter to eliminate certain wavelengths of light.

Different colour lights (RBG) uses additive properties to bring light of a certain color to our eyes.

Color synthesis is the art of forming different types of colours from small number of primary colours. The color formed is called a secondary color.

Color synthesis is carried out through the following means:

In additive color synthesis, the three primary colours lights that are combined is Red(R), Blue (B) and Green(G).

The wavelength from the various color light combine to generate white light which is visible to the eye.

Therefore, different colour lights (Red, Blue and Green) uses additive properties to bring light of a certain color(white) to our eyes.

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Answer:

A and D are the answers

Explanation:

the other two don't make sense

The statements C and D are correct, i.e., curly hair have different protein structure from straight hair and curly hair results from a change in the gene.

Proteins are biomolecules made of amino acids. Proteins are very essential to all living things and contributes the body structure. Proteins are mainly up taken through diet and they are the main source of energy.

Hair is made of keratin protein. Keratin makes up our skin and nails too.Curly hair is originating by birth not developing over time. Curly hair is more likely to be occurring through inheritance.

The protein structure the hair follicle is some more bend for curly hair. Curly hair and straight hair originates from different gene traits. The gene type is inherited from the parents.

Hence, for people with curly hair have different protein structure and it result from a change in gene that code for hair structure. Thus options C and D are correct.

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Answer: Volatile compounds present in the fresh sage leaf or mint leaf evaporate on rubbing.

Explanation:

When fresh sage or mint is rubbed on the skin or any other surface the volatile chemicals associated with the integral structure of the plant part get evaporated in the surrounding air and the vapors can be detected by the olfactory receptors present in the nose. These receptors take the smell or fragrance stimulus and generate impulses or signals which goes to brain and brain interprets the smell or fragrance.

Explanation:

2KCLO3 (s) = 2KCl (s) + 3O2 (g)

Answer:

Mass of Cl = 35.5

Mass of Cl2 => 35.5×2

=> 71 g/mol

hope that helps ✌

71

The atomic mass of chlorine is equal to the molar mass of chlorine so the molar mass of chlorine is 35.5

=> molar mass for Cl^2: 35,5*2=71

1. Unit of pressure called a derived unit because it is a combination of base units (kg·m^-1·s^·2).

2. We measure the volume of milk by a instrument called Milk Lactometer.

Explanation:

a chemical reaction in which the rate of reaction is proportional to the concentration of each of three reacting molecules

Answer:

Common diatomic molecules include hydrogen (H2), nitrogen (N2), oxygen (O2), and carbon monoxide (CO). Seven elements exist as homonuclear diatomic molecules at room temperature: H2, N2, O2, F2, Cl2, Br2, and I2. The bond in a homonuclear diatomic molecule is non-polar due to the electronegativity difference of zero.

Answer:

82 °C

Explanation:

Let the specific heat capacity of the coffee be that of water which is 4.2 J/g °C.

Now, at the final temperature, heat gained by Aluminum spoon ,Q equals heat lost by coffee, Q'.

Q = -Q'

Q = m₁c₁(T₂ - T₁) where m₁ = mass of aluminum spoon = 45 g, c₁ = specific heat of aluminum = 0.88 J/g °C, T₁ = initial temperature of aluminum spoon = 24 °C and T₂ = final temperature of aluminum spoon.

Q' = m₂c₂(T₂ - T₃) where m₂ = mass of coffee = 180 g, c₂ = specific heat of coffee = 4.2 J/g °C, T₃ = initial temperature of coffee = 85 °C and T₂ = final temperature of coffee.

So, Q = -Q'

m₁c₁(T₂ - T₁) = -m₂c₂(T₂ - T₃)

Making T₂ subject of the formula, we have

m₁c₁T₂ - m₁c₁T₁ = -m₂c₂T₂ + m₂c₂T₃

m₁c₁T₂ + m₂c₂T₂ =  m₂c₂T₃ + m₁c₁T₁

(m₁c₁ + m₂c₂)T₂ =  m₂c₂T₃ + m₁c₁T₁

T₂ =  (m₂c₂T₃ + m₁c₁T₁)/(m₁c₁ + m₂c₂)

substituting the values of the variables into the equation, we have

T₂ =  (180 g × 4.2 J/g °C × 85 °C + 45 g × 0.88 J/g °C × 24 °C )/(45 g × 0.88 J/g °C  + 180 g × 4.2 J/g °C)

T₂ =  (64260 J + 950.4 J)/(39.6 J/°C  + 756 J/°C)

T₂ =  65210.4 J/795.6 J/°C

T₂ =  81.96 °C

T₂ ≅  82 °C

Answer:

D

Explanation:

according to boyle's law the temperature and pressure of a gas are inversely proportional given by the equation

p1v1=p2v2

In this case p1 is 9.5,v1 is 1.7,v2 is 1.1 and we have to find p2

9.5×1.7=p2×1.1

16.15/11=1.1p2/1.2

p2=14.7

I hope this helps

Answer:

[tex]\boxed {\boxed {\sf D.\ 14.7 \ atm}}[/tex]

Explanation:

We are asked to find the pressure on a gas given a change in volume. We will use Boyle's Law which states the volume of a gas is inversely proportional to the pressure. The formula for this law is:

[tex]P_1V_1=P_2V_2[/tex]

The gas originally has a pressure of 9.5 atmospheres and a volume of 1.7 liters.

[tex]9.5 \ atm * 1.7 \ L = P_2V_2[/tex]

The gas is compressed to a volume of 1.1 liters, but the pressure is unknown.

[tex]9.5 \ atm * 1.7 \ L = P_2* 1.1 \ L[/tex]

We want to find the new pressure, so we must isolate the variable P₂. It is being multiplied by 1.1 liters. The inverse operation of multiplication is division. Divide both sides of the equation by 1.1 L.

[tex]\frac {9.5 \ atm * 1.7 \ L}{1.1 \ L} =\frac{ P_2* 1.1 \ L}{1.1 \ L}[/tex]

[tex]\frac {9.5 \ atm * 1.7 \ L}{1.1 \ L} =P_2[/tex]

The units of liters cancel.

[tex]\frac {9.5 \ atm * 1.7 }{1.1 } =P_2[/tex]

[tex]\frac {16.15}{1.1} \ atm =P_2[/tex]

[tex]14.6818181818 \ atm= P_2[/tex]

Round to the tenths place. The 8 in the hundredth place tells us to round the 6 up to a 7.

[tex]14.7 \ atm \approx P_2[/tex]

The new pressure at a volume of 1.1 liters is approximately 14.7 atmospheres.

Answer:

0⁰c , 5 mmHg

Explanation:

Because at this temperature we all know water can be in state of both solid and liquid and when pressure is decreased it can be in form of gas too

Answer:

mSn=0.24375*59=14.38125

Explanation:

nHBr=1.3*0.75=0.975

nSn=1/4nHBR=0.975/4=0.24375

mSn=0.24375*59=14.38125

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The pressure in atm exerted by 1.8 g of H₂ gas exert in a 4.3 L balloon at 27ºC is 5.12 atm

The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).

Let's convert grams to moles (via molar mass).

Molar Mass (H₂) :  2 (1.008 g/mol)

Molar Mass (H₂) :  2.016 g/mol

1.8 grams H₂               1 mole

----------------------  x  ----------------------  =  0.893 moles H₂

                                2.016 grams

The Ideal Gas Law equation looks like this:

PV = nRT

In this equation,

After converting Celsius to Kelvin, you can put the given values into the equation and simplify to find the pressure.

P = ? atm                                R = 0.0821 L*atm/mol*K

V = 4.3 L                               T = 27 °C + 273.15 = 300.15 K

n = 0.893 moles

PV = nRT

P (4.3 L) = (0.893 moles) (0.0821 L*atm/mol*K)( 300.15 K)

P (4.3 L) =  22.0021

P = 5.12 atm

Therefore, The pressure in atm exerted by 1.8 g of H₂ gas exert in a 4.3 L balloon at 27ºC is 5.12 atm

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Answer:

increase temperature, increase surface areas, add catalyst, stir

The rate of reaction can be increased with the increase in temperature, surface area, adding catalyst and allowing stirring. Thus, option C is correct.

The rate of reaction is given as the rate of formation of product or the rate of disappearance of reactant in unit time.

The rate of reaction can be affected with:

Thus, the rate of reaction can be increased with the increase in temperature, surface area, adding catalyst and allowing stirring. Thus, option C is correct.

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Answer:

K = [N2] [Cl2]³ / [NCl3]²

Explanation:

The equilibrium expression, K, of a reaction:

aA + bB ⇄ cC + dD

Is defined as the ratio between the multiplication of concentrations of products powered to its reaction coefficient and the multiplication of concentrations of reactants powered to its reaction coefficient as follows:

K = [C]^c[D]^d / [A]^a[B]^b

Now, for the reaciton:

2NCl3 ⇄ N2(g) + 3Cl2(g)

K is:

K = [N2] [Cl2]³ / [NCl3]²

On changing the ratio of baking soda and vinegar changes the amount of carbon dioxide produced is true, because each species will depends on both reactants.

Chemical reaction between baking soda and vinegar is shown below in the attached image in which the formation of carbon dioxide, water and sodium acetate takes place. So the formation of carbon dioxide depends on the baking soda and baking soda reacts with vinegar to form sodium acetate so change in the ratio will changes the amount of carbon dioxide.

Hence on changing the ratio of reactants and vinegar changes the amount of carbon dioxide.

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Answer:

option C 11

is the correct answer

Answer:

Explanation:

There are 353 grams of H2SO4 in 3.60 moles of H2SO4.

Answer:

In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule in atomic or molecular orbitals.

Answer:

I could be wrong letter c

Answer:

volume gives a larger source of error in determination of density

Answer:

Density and volume are inversely proportional. The greater the volume, the lower the density.

Density= Mass/ Volume

Explanation:

Density= Mass/ Volume

A volume error may be due to the measuring instrument used. Different instruments have different resolutions, and therefore varying percentage uncertainties. An instrument with a higher resolution has a lower percentage error. A pipette will give a more accurate reading compared to a beaker. Density and volume are inversely proportional. The greater the volume, the lower the density.

Parallax error could also lead to inaccurate volume readings. The volume reading must be taken below the meniscus for a liquid such as water and above the meniscus for a liquid such as mercury.

Another source of error is the measurement of mass. Instruments that are used to determine mass have different percentage uncertainties. An electronic weighing scale is most likely to give an accurate reading. Density is directly proportional to mass. The greater the volume of the liquid, the greater its density.

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Answer:

2.03 atm

Explanation:

Number of moles of He = 1g/4g/mol = 0.25 moles

Number of moles of F2 = 14.0g/38 g/mol = 0.37 moles

Number of moles of Ar=19.0g/40g/mol = 0.48 moles

Total number of moles = 0.25 + 0.37 + 0.48 = 1.1 moles

From;

PV=nRT

P= pressure of the gas mixture

V= volume of the gas mixture

n= total number of moles of the gas mixture

R= gas constant

T= temperature of the gas mixture

P= nRT/V

P= 1.1 × 0.082 × 293/13

P= 2.03 atm

Answer:

D .

Explanation:

Individuals are all equally likely to successfully reproduce, but the genome will mutate to erase harmful traits.