Use Hess's Law to calculate the enthalpy change for the reaction
WO3(s) + 3H2(g) => W(s) + 3H2O(g)
from the following equations:
2W(s) + 3O2(g) => 2WO3(s) DH = -1685.4 kJ
2H2(g) + O2(g) => 2H2O(g) DH = -477.84 kJ

The correct options are: shining dim blue light on a strip of metal, and

shining bright blue light on a strip of metal produces a photoelectric

effect. Hence, option (C) and (D) are correct

The photoelectric effect is the emission of electrons from a metallic surface when light of determined frequency shines over the metallic surface.

The electrons are ejected from the metal surface when the frequency of the incident light beam reaches a minimum frequency (threshold).

The frequency of light is  related to the color of light (not with the intensity).

The red light is at the lower frequency end and the violet light at the higher frequency end of the spectrum of visible light.

That condition  is considered in the given statement when it tells that "Blue light waves have more energy than red light waves" , since the frequency is directly related to the energy, by the Planck equation:

Energy of a photon (light) = Planck constant × frequency.

The intensity of the light (if the light is dim or bright) does not influence the photoelectric effect.

Hence, you conclude that the light with more energy (the blue light) either dime or bright will most likely produce the photoelectric effect.

That is why the correct options are:

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Answer:

- Communication between scientists increased.

- Technological advancements were made.

Explanation:

The complete question is

Which answer choices correctly describe why the number of known elements more than doubled by 1861?

Select all that apply.

 -  Metalworkers began using new metals.

- Communication between scientists increased.

- The American Civil War started.

- Technological advancements were made.

Technological advancement allowed more elements to be properly analysed and classified, and knowledge sharing between scientist by means of communication made it possible for the known number of elements to double by 1861

6.02 x10^23 atom  

3.5g x 1mol/63.55g Cu x 6.02 x 10^23/ 1mol=

3.32 x 10^22 atoms

Answer:

rate = k [H2O] [NO]²

Explanation:

[H2] (M) [NO] (M) Rate (M/s)

Trial 1 0.35 0.30 2.835 x 10-3

Trial 2 0.35 0.60 1.134 x 10-2

Trial 3 0.70 0.60 2.268 x 10-2

Comparing Trial 1 and 2 , the rate of the reaction increases by a factor of 4 when the concentration of NO was doubled. This means that the reaction is second order with respect to NO

Comparing Trial 2 and Trial 3, the rate of reaction increased by a factor of 2 when the concentration of H2O was doubled. This means that the reaction is first order with respect to H2O

The rate law fr the reaction is given as;

rate = k [H2O] [NO]²

Answer:

9.8 × 10^21

Explanation:

Equation of the reaction;

Cd(s) + Ni^2+(aq) ----> Cd^2+(aq) + Ni(s)

E°cell= E°cathode - E°anode

E°cathode= -0.25 V

E°anode = -0.40 V

E°cell= -0.25 - (-0.40)

E°cell = 0.65 V

∆G= -nFE°cell

∆G= -(2 × 96500 × 0.65)

∆G = -125450 J

From;

∆G= -RTlnK

lnK = ∆G/-RT

K= e^∆G/-RT

K= e^-[-(125450/8.314 × 298)]

K= 9.78 × 10^21

Answer:

The answer is

Explanation:

The kinetic energy of a body can be found by using the formula

where

m is the mass

v is the velocity / speed

From the question

mass = 10 kg

velocity = 12 m/s

Substitute the values into the above formula and solve

That's

We have the final answer as

Hope this helps you

Answer:

volume = 15

density = 10

Explanation:

mass = 150 grams

volume = 45 - 20 = 15

density = mass / volume

density = 150 / 15 = 10

Answer:

[tex]m=2.575g[/tex]

Explanation:

Hello,

In this case, since the density is defined as the ratio of the mass and volume:

[tex]\rho =\frac{m}{V}[/tex]

We can compute the mass of blood as follows:

[tex]m=\rho *V=1.03g/L*2.500L\\\\m=2.575g[/tex]

Best regards.

Answer:

8.34 moles

Explanation:

We are given 8.34 moles.

We need to find moles: 8.34

Answer:

[tex]\mathbf{\Delta E = 2.042 \times 10^{-19} \ J}[/tex]

Explanation:

Using the Rydberg expression to calculate the change in energy of a photon emitted, we have :

[tex]\Delta E = R ( \dfrac{1}{n_f^2}-\dfrac{1}{n_i^2})[/tex]

where;

R = Rydberg constant = [tex]2.178 \times 10 {-18} \ J[/tex]

[tex]n_f[/tex] = 1    and [tex]n_i[/tex] = 4

replacing our values into equation, we get:

[tex]\Delta E = 2.178 \times 10^{-19} (\dfrac{1}{1^2}-\dfrac{1}{4^2})[/tex]

[tex]\Delta E = 2.178 \times 10^{-19} (\dfrac{1}{1}-\dfrac{1}{16})[/tex]

[tex]\Delta E = 2.178 \times 10^{-19} (\dfrac{15}{16})[/tex]

[tex]\mathbf{\Delta E = 2.042 \times 10^{-19} \ J}[/tex]

Answer:

Xenon

Explanation:

Step 1: Given data

Step 2: Convert the temperature to Kelvin

K = °C + 273.15 = 100.0°C + 273.15 = 373.2 K

Step 3: Calculate the number of moles (n)

We will use the ideal gas equation.

P × V = n × R × T

n = P × V / R × T

n = 1.00 atm × 0.335 L / (0.0821 atm.L/mol.K) × 373.2 K

n = 0.0109 mol

Step 4: Calculate the molar mass of the gas

M = 1.44 g / 0.0109 mol = 132 g/mol

Step 5: Identify the gas

The gas with a molar mass of about 132 g/mol is xenon.

The gas with a molar mass of 132.11g/mol is Xenon. Hence the unknown gas is Xenon

Using the ideal gas equation

[tex]PV=nRT\\n=\frac{PV}{RT}[/tex]

R is the Boltzmann constant = 8.31

V is the volume of the gas = 0.355L

P is the pressure = 1.00atm

T is the temperature of the gas = 100.0°C = 373K

To get the unknown gas, we need to first get the number of moles of gas:

[tex]n=\frac{1.0\times 0.335}{0.0831 \times 373}\\n=0.0109 moles[/tex]

Get the molar mass of the element;

[tex]n=\frac{m}{M}\\0.0109=\frac{1.44}{M}\\M=\frac{1.44}{0.0109}\\M= 132.11g/mol[/tex]

The gas with a molar mass of 132.11g/mol is Xenon. Hence the unknown gas is Xenon

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Answer:

Product one: (2S, 3R)-3-chloro-2-butanol

Product two: (3S, 2R)-3-chloro-2-butanol

Explanation:

The IUPAC  name of the products following IUPAC guidelines are :

Product one: (2S, 3R)-3-chloro-2-butanol

Product two: (3S, 2R)-3-chloro-2-butanol

attached below is a pictorial representation of the formation of the 3-chloro-2-butanol via backside attack of Nucleophile

Answer:

D

Explanation:

Because jwbahaggagqhhwjwjja

Answer:

In order to determine the mass of a substance given the volume, we require the density. The density of iron is 7.87 grams/cm³

Density = mass / volume

Mass = density * volume

Mass = 7.87 * 4.8

37.776 grams of iron are present in the cube

The density of the substance represents the relation of the mass to the volume of the substance. The mass of a pure iron cube of density 7.87 grams/cm³ is calculated to be 37.632 grams.

Mass is the amount of the substance contained that when gets divided by the volume in liters, milliliters or cubic centimeters gives the density of the substance. The mass of the substance can be in grams, kilograms, milligrams, etc.

The mass (m) is the multiplication product of the density (D) and volume (V) of the substance. Mass measures the amount whereas density measures the space occupied by the volume of the substance.

Given,

Density of iron cube (D) = 7.87 grams/cm³

Volume of cube (V) = 4.80 cm³

The formula is given as:

Density = mass ÷ volume

Mass = density × volume

Substituting values from above, the mass in grams of the iron cube is calculated as:

mass = 7.87 grams/cm³ × 4.80 cm³

mass = 37.632 grams

Therefore, the iron cube with a density of 7.87 grams/cm³ has a mass of 37.632 grams.

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Answer:

[tex]p_{PCl_3}=0.693atm\\\\p_{Cl_2}=0.693atm\\\\p_{PCl_5}=0.967atm[/tex]

Explanation:

Hello,

In this case, for the given reaction, the equilibrium expression is:

[tex]Kp=\frac{p_{PCl_3}p_{Cl_2}}{p_{PCl_5}}[/tex]

But in terms of the reaction extent [tex]x[/tex] can also be written as:

[tex]Kp=\frac{x*x}{p_0-x}[/tex]

Whereas the initial pressure is 1.66 atm. Thus, we write:

[tex]0.497=\frac{x^2}{1.66atm-x}[/tex]

And solving for [tex]x[/tex] we obtain:

[tex]x=0.693atm[/tex]

Therefore, the pressure of each species at equilibrium is:

[tex]p_{PCl_3}=x=0.693atm\\\\p_{Cl_2}=x=0.693atm\\\\p_{PCl_5}=1.66atm-0.693atm=0.967atm[/tex]

Best regards.

Answer:

The average persons requires 75000 breaths to exhale 1.0 Kg of fat

Explanation:

Note: The question is incomplete. The complete question is given below:

"The human body burns glucose (C6H1206) for energy according to this chemical reaction:

C6H1206 + 602----> 6CO2 + 6H20

The products of the reaction are carbon dioxide (CO2) and water (H20). Interestingly, all of the carbon dioxide and much of the water exits the body through the lungs: on every breath, the average person exhales 500 mL of air, which is typically enriched to 4% CO2 and 5% water vapor by volume. In short, when a person loses weight by dieting, the weight that is lost actually departs his body as a gas, every time he exhales. Each kilogram of body fat lost requires exhaling about 3.0 kg of carbon dioxide. Calculate how many breaths it takes an average person to "exhale" 1.00 kg of fat. Round your answer to the nearest thousand. You'll need to know that the density of CO2 is 2.0 kg/m³”.

Volume of air exhaled on average per breath = 500 mL

Volume of CO2 exhaled per breath = 4/100 × 500 = 20 mL

Since, 1000000 mL = 1 m³;

20 mL = 0.00002 m³

3.0 kg of CO2 is exhaled per Kg of fat.

Density of CO2 = 2.0 Kg/m³

Volume = mass/density

Volume of 3.0 Kg CO2 = 3.0/2.0 = 1.5 m³

Number of breaths that will have a volume of 1.5 m³ = 1.5/0.00002 = 75000 breaths.

Answer:

[tex]r_B=k[A][B]^3[/tex]

Explanation:

Hello,

In this case, in order to represent the rate disappearance of B, we need to consider the rate law as:

[tex]r_B=k[A][B]^3[/tex]

Whereas k is the rate constant the third power corresponds to B's stoichiometric coefficient as well as the concentrations of A and B because they are involved in the overall rate too.

Regards.

Answer:

2NaCl > Cl2 + 2Na

Explanation:

2 moles of sodium chloride is irreversible to chlorine gas plus 2 moles of solid sodium

Solid sodium chloride decomposes into chlorine gas and solid sodium balanced chemical equation will be 2NaCl → [tex]2 Na^{+} + 2Cl^{-}[/tex].

An equation with equal proportions of each kind of atom from both ends of the arrow would be called a balanced chemical reaction. A written symbolic description of a chemical reaction will be known as a chemical equation. The reactant chemical(s) were listed on the left, while the product chemical(s) were listed on the right.

Chemical equation is just the presentation of a chemical reaction using symbols and equations for the ingredients.

Solid sodium chloride decomposes into chlorine gas and solid sodium balanced chemical equation will be 2NaCl → [tex]2 Na^{+} + 2Cl^{-}[/tex].

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Answer:

75.15 g/mol

Explanation:

First, let us look at the equation of reaction;

[tex]NaOH + HAA --> NaAA + H_2O[/tex]

From the balanced equation of reaction, 1 mole of NaOH is required to completely neutralize 1 mole of HAA.

Recall that: mole = molarity x volume.

Therefore, 27.50 mL, 0.120 M NaOH = 0.0275 x 0.120 = 0.0033 moles

0.0033 mole of NaOH will therefore requires 0.0033 moles of HAA for complete neutralization.

In order to find the molar mass of the unknown amino acid, recall that:

mole = mass/molar mass, hence, molar mass = mass/mole.

Therefore, molar mass of HAA = 0.248/0.0033 = 75.15 g/mol

Answer:

b

Explanation:

The correct answer would be requiring individuals to complete specific types of work.

A question of how to produce deals with the processes of production itself. There are several small processes that eventually aggregate together to lead to the production of goods or services. Some of these small processes will definitely require that individuals within the production unit complete specific types of work.

The option of growing corn instead of potatoes and producing more capital goods and fewer consumer products address what to produce while the option of selling natural resources to other countries has to do with for whom to produce.

Correct option: b

Answer:

0.0075÷0.015=0.5 not so sure lol

Answer:

This is an exothermic reaction.

Explanation:

You can calculate the reaction using the calculation below:

ΔH reac=  3(413Kj/mol) +358Kj/mol +467 Kj/mol +1070 kj/mol = 3134 kj/mol

ΔH prod = 3(413 kj/mol) + 347 kj/mol + 358kj/mol +467kj/mol +745 kj/mol = 3156kj/mol

ΔH = 3134 kj/mol - 3156kj/mol = -22 Kj/mol

Negative results indicate an exothermic reaction.

An image of the reaction is attached below.

The heat of the reaction has been -22 kJ/mol. The negative sign has been the indication of the exothermic reaction.

The heat of reaction has been given as the amount of energy absorbed or released by the system to form the products.

The heat of reaction has been given by:

[tex]\Delta H=\Delta H_{reactant}-\Delta H_{product}[/tex]

The heat of reaction has been calculated based on the bond energies. The energy constituent by each bond in the reactant has been the heat of the reactant, and the energy of product has been the heat of product.

The reactant molecules have been [tex]\rm CH_3OH[/tex] and [tex]\rm C\equiv O[/tex].

The bond energy of the reactant has been:

[tex]\Delta H_{reactant}=3\;\times \;\text {C-H}\;+\;\text{C-O + O-H}+\;\text C\equiv \text O\\ \Delta H_{reactant}=3\;\times \;413\;+\;358+467+1070\;\text{kJ/mol}\\ \Delta H_{reactant}=3134\;\text{kJ/mol}[/tex]

The heat of reactant has been 3134 kJ/mol.

The product molecule has been [tex]\rm CH_3COOH[/tex]

The bond energy of the product has been:

[tex]\Delta H_{product}=3\;\times \;\text {C-H}\;+\;\text{C-O + O-H +\;C-C}+\;\text C=\text O\\\Delta H_{reactant}=3\;\times \;413\;+\;358+467+\;347\;+\;745\;\text{kJ/mol}\\\Delta H_{reactant}=3156\;\text{kJ/mol}[/tex]

The heat of product has been 3156 kJ/mol.

The heat of reaction has been given as:

[tex]\Delta H=\Delta H_{reactant}-\Delta H_{product}\\ \Delta H=3134-3156\;\text{kJ/mol}\\ \Delta H=-22\;\rm kJ/mol[/tex]

The heat of the reaction has been -22 kJ/mol. The negative sign has been the indication of the exothermic reaction.

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Answer:

D will brain cancer eventually be curable?

Explanation:

Answer:

Do foods that contain a high amount of fat cause brain cancer?

Explanation:

Do foods that contain a high amount of fat cause brain cancer?

Answer:

Oxidation Occurs after the addition of the uncoupler 2,5 dinitrophenol

Explanation:

The chemical compound that is Dinitrophenol (DNP). The compound has the chemical formula of HOC6H3(NO2)2. The compound helps during Adenosine triphosphate synthesis by making sure that there is enough hydrogen ion for the synthesis.  

Therefore, if the " presence of oxygen and in the absence of ADP". Thus,  When the uncoupler 2,4-dinitrophenol is added to a suspension of normal mitochondria five minutes after an oxidizable substrate has been added, there is going to be OXIDATION ON THE SUBSTRATE AFTER THE ADDITION WHICH IS GOING TO BE RAPID AFTER SOME TIME.

Answer:

The ancient Greeks were the first to use the word atom,which means indivisible,to describe the smallest particle of any substance. Its actual existence was not established until yhe nineteenth century when John Dalton, an English chemist,put forward a theory to describe the nature of the atom.The atom is now considered to be the basic unit of simple substances or elements.An atom is the smallest particle of an element which can take part in a chemical reaction or an atom is the smallest part of an element that can ever exist and still possess the chemical properties of that element.

Answer:

4) All of the above.

Explanation:

Hello,

In this case, considering the attached picture wherein the Lewis dot structure is drawn, we realize that the nitrogen has a lone par of electrons, whereas the other three valence electrons are bonded with the three hydrogen atoms in order to obey the octet rule and form three bonding pairs for nitrogen and one bonding pair per hydrogen. Therefore, answer is 4) All of the above.

Regards.

Answer:

The answer is 22 degrees celsius. which is D.

Explanation:

Hot:84-99 F (29-37.5 C) Warm:70-84 F (21-29 C) Cool:55-69 F (13-21 C) Cold: Below 55 F (Below 13 C)

Answer: 22

Explanation: UsaTestPrep

Answer:

The answer is NH3.

Explanation:

The N2H2 (O hydrazine) is formed when from the synthesis of ammonia and hydrogen peroxide.

Or also formed when a 1,000g sample of nitrogen is combined with a 7.2 x10∧-2 sample of hydrogen.

0.2160 of hydrogen is 3 times 7.2 x10∧-2.

It means that the compound would look like:

N2H6.

But in chemistry, if there are divisible numbers in a compound, they must be divided:

NH3.

Answer:

THE MASS OF THE SAMPLE IS 25.37 g

Explanation:

Using PV = m RT / Mm

P = 0.945 atm

V = 1550 mL = 1.55 L

R = 0.082

T = 50 C

m = unknown

Mm = molar mass = 35.5 * 2 = 71 g/mol

Re-arranging the formula by making m the subject of the equation, we have:

m = PV Mm / RT

m = 0.945 * 1.55 * 71 / 0.082 * 50

m = 103.99725 / 4.1

m = 25.37 g

The mass of the sample is therefore 25.37 g