Answer:
Answer:
A)6.6×10^22atoms of Pt in the cube
B)1.4×10^-8m
Explanation:
(a) Calculate the number of Pt atoms in the cube.
an edge length of platinum (Pt) = 1.0 cm.
Then Volume= 1.0 cm×1.0 cm×1.0 cm=1cm^3
Then we have volume of the cube as 1cm^3
Given:
The density Pt = 21.45 g/cm3
the mass of a single Pt atom =3.240 x 10^-22 g
Then with 1atom of the platinum element, we can calculate the number of Pt atoms in the cube as
Density of pt/mass of a single Pt atom
=(21.45 /=3.240 x 10^-22)
=6.6×10^22atoms of Pt in the cube
B)Volume of cube V=4/3πr^3
V= 4/3 ×π×r^3
V= 4.19067r^3
r^3= V/4.19067
But volume is not total volume but just 74% of it, then With 74% of the space inside the cube is taken up by Pt atoms, then we need to find 74% of volume of the cube which is 1cm^3
74/100 ×1= 0.74cm^3
Then our new volume V is 0.74cm^3
r^3=0.74/4.19067×6.620 x 10^22
r^3=2.6674×10^-24
r= 3√2.6674×10^-24
r=1.4×10^-8m
The energy of a photon is 4.23 x 10-17 J. What is the wavelength of the radiation?
The wavelength of the radiation is 4.7 x 10⁻⁹ m
What is the Einstein's Formula for Energy?
The energy
E is given, from Einstein's formula, as:
E=h⋅ν
Where:
h=6.63×10⁻³⁴Js is Planck's constant;
ν is the frequency.
You can relate frequency and wavelength
λ through the speed of light c as:
c=λ⋅ν
So finally you get:
E=hc/λ
It is given in the question
The energy of a photon is 4.23 x 10⁻¹⁷ J.
Wavelength = ?
λ = hc/E
λ = 6.63×10⁻³⁴x 3 x 10⁸ / 4.23 x 10⁻¹⁷
λ = 4.7 x 10⁻⁹ m
Therefore the wavelength of the radiation is 4.7 x 10⁻⁹ m .
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The first four electrons shells fill out in what electron configuration?
Apparently the answer is 2,8,8,2. Why?
Explanation:
2, 8, 8, 2 is the electron arrangement of Calcium.
The way that the "orbitals", the shells, fill up is given as
[tex]1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 4s^{2} 3d^{10}[/tex] . . . etc etc.
It is more stable for the fourth shell to start filling up with an electron pair, and then subsequent electrons filling up the third shell again.
So while potassium 19, is 2,8,8,1
And calcium 20, is 2,8,8,2
Scandium 21 will fill up as, 2,8,9,2
This will continue until we reach Zinc 30, which will fill up as 2,8,18,2. The third shell is now "full", and the fourth shell will now being to fill up.
The fourth orbital starts getting filled up again, Gallium 31, is 2,8,18,3
A certain atom has 22 protons and 19 electrons. This atom loses an electron. The net charge on the atom is now 4+. If this same atom with 22 protons and 19 electrons were to gain 3 electrons, the net charge on the atom would be
Answer: 0
Explanation:
If 3 electrons were to be gained, then the number of protons would equal the number of electrons.
For the reaction N2O4(g) 2 NO2(g), Kc = 0.21 at 100 C. At a point during the reaction, [N2O4]=0.12 M and [NO2]=0.55M. Is the reaction at equilibrium? If not, in which direction is it progressing?
The equilibrium constant shows the extent to which reactants are converted into products.
In this case, we must find the reaction quotient as follows;
Qc = [0.55]^2/[0.12] = 2.5
Since the Qc > Kc, it means that the reverse direction is favored in this reaction.
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A student didn't notice that her pipette tip was broken. She used the pipette properly but it consistently delivered 4.70 cm³ of vinegar instead of the desired 5.00 cm³. How would the percent by mass results obtained have been affected? Explain your answer.
The mass % will be affected by 0.25%.
What is mass percentage ?Mass Percentage is defined as the grams of solute per gram of solution , multiplied by 100%
It is given that
She used the pipette properly but it consistently delivered 4.70 cm³ of vinegar instead of the desired 5.00 cm³.
Mass Percentage affected = ?
Mass is directly proportional to the volume
For calculating ratios of the same compound the density can be neglected
the density of vinegar is 1.05 gm/cm³
mass for 5cm³= 5*1.05 = 5.25gm
mass for 4.75 cm³ = 4.9875 gm
for 100 gm solution
mass% expected = 5.25* 100/100 = 5.25%
mass % (actual) = 4.9875 / (100-0.2625) = 5%
Therefore the mass % will be affected by 0.25%.
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3) A gas has a volume of 15.0 mL at a pressure of 1.05 atm. What is the volume of the gas at
a pressure of 0.450 atm?
Answer:
V⬇2=64.mL this is the answer and the 2 is supposed to be at the bottom which the arrow stands for so do not put the arrow with that
What happens if i don’t pass the chemistry regent?
Answer:
You will typically get another chance to retake the exam
Answer:
well you either have a chance to retake the test if your teacher or just not let you take it at all. you have to pass 4 regents test including chemistry in order to get a regent diploma. so you can either retake or it you just failed it.
What is the molality of this solution of table sugar in water?
The molality of the sugar solution is 0.034 mol/kg.
The molality and molarity of a chemical solution are equivalent for aqueous solutions of covalent molecules, such as sugar.
does hot ice have to be cold or hot?
Answer:
hot
Explanation:
You'll need to boil the solution, though, to reduce the amount of water so that it is concentrated enough to form crystals. Cook your solution over low to medium heat for about an hour. You want to reduce it down to 1 cup or less.
Energy and Enthalpy Changes, Heat and Work -- Monatomic Ideal Gas dynamically generated plot 2.00-mol of a monatomic ideal gas goes from State A to State D via the path A→B→C→D: State A PA=11.0atm, VA=12.50L State B PB=11.0atm, VB=7.00L State C PC=25.0atm, VC=7.00L State D PD=25.0atm, VD=20.50L Assume that the external pressure is constant during each step and equals the final pressure of the gas for that step. Calculate q for this process. q = 1pts Tries 0/6 Calculate w for this process. w = -902 J Use w = -PΔV and sum over the individual steps. Check that you have the correct energy units and be sure you have the sign right (w is defined as the work done ON THE SYSTEM). 1pts Incorrect. Tries 4/6 Previous Tries Calculate ΔE for this process ΔE = 1pts Tries 0/6 Calculate ΔH for this process. ΔH = 1pts
(a) The heat generated in the process is 28 kJ.
(b) The work done in the process is determined as -28 kJ.
(c) The change in the internal energy is 0.
Heat of the isothermal compression
The heat generated in the process is negative done in the process.
W = -PΔV
W = -P(V₂ - V₁)
From A to BW = -P(VB - VA)
W = -11(7 - 12.5)
W = 60.5 L.atm = 60.5 x 101.325 J/L.atm = 6,130.16 J
From C to DW = -25(20.5 - 7)
W = -337.5 L.atm = -34,197.18 J
Total work , w = -34,197.18 J + 6,130.16 J = -28 kJ
q = - w
q = 28 kJ
Change in internal energyΔE = q + w
ΔE = 28 kJ - 28 kJ = 0
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What information does the potential energy diagram reveal about a reaction?
A. It shows what the enthalpy of formation is for each molecule.
B. It shows the changes in kinetic energy of the molecules.
C. It shows what phase changes occurred during the reaction.
D. It shows whether the reaction is exothermic or endothermic.
Answer: It shows whether the reaction is exothermic or endothermic.
Explanation:
If the potential energy of the products is greater than that of the reactants, then the reaction is exothermic.If the potential energy of the reactants is greater than that of the products, then the reaction is endothermic.PLEASE HELP!
The vapor pressure of benzene at 25 °C is 95.1 mm Hg and of toluene 28.4 mm Hg. The mass fractions of benzene and toluene in a solution are 0.5.
a) Calculate the partial pressure of benzene and toluene above the solution.
b) Calculate the total vapor pressure above the solution.
c) Calculate the vapor composition above the solution.
Benzene be B
Toluene be T
We have made then one lettered to make things easier
[tex]\sf P^0_B=95.1mmHg,P^0_T=28.4mmHg[/tex][tex]\sf x_B=x_T=0.5[/tex][tex]\\ \rm\Rrightarrow \dfrac{P^0_B-P_B}{P^0_B}=x_B[/tex]
[tex]\\ \rm\Rrightarrow 95.1-P_B=95.(0.5)[/tex]
[tex]\\ \rm\Rrightarrow 95.1-P_B=47.55[/tex]
[tex]\\ \rm\Rrightarrow P_B=47.55mmHg[/tex]
And
[tex]\\ \rm\Rrightarrow \dfrac{P^0_T-P_T}{P^0_T}=x_T[/tex]
[tex]\\ \rm\Rrightarrow 28.4-P_T=28.4(0.5)[/tex]
[tex]\\ \rm\Rrightarrow P_T=14.2mmHg[/tex]
Total vapour pressure
28.4+95.1123.6mmHgHow do I create an atom with a mass of 3 and a neutral charge?
Answer:
a lithium atom (Z=3, A=7 AMU) contains three protons (found from Z), three electrons (as the number of protons is equal to the number of electrons in an atom), and four neutrons (7 – 3 = 4).
Explanation:
What is the source of the forces that move the tectonic plates along this plate
boundary?
A. Differences in density between two different types of oceanic
crust
OB. Convection currents in the mantle
C. Convection cur nts in the ocean
D. Differences in density between oceanic crust and continental crust
The source of the forces that move the tectonic plates along this plate
boundary is the convection current in the mantle. Hence, the correct
option in option (B)
What are Tectonic plates ?Tectonic plates refers to the Spheres that are found in the uppermost Mantle of the Earth .
The Tectonic plates are also called the Litosphere .
The Motion of the Plates about the axis causes the Tectonic demarcations which are Know as the
Convergent
Divergent
Transform
Now these Plate are formed by the Convection of Currents in the Earths's Mantle
That is, the Dynamics of Current in and around the Earths Mantle brings about the tectonic plates
Hence the the correct option in option (B)
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Convection currents in the mantle is the source of the forces that move the tectonic plates along this plate boundary and is denoted as option B.
What is Convection?This is referred to the process of heat transfer in a fluid such as gases and liquids.
The convection currents in the mantle is responsible for the force present in the tectonic plates.
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8. (02.04 MC)
The partial electron configuration of an atom with 14 electrons is shown.
1s²2s²2p63s²x
Which of the following does X represent? (3 points)
2d²
3s²
3p²
4s²
E
Answer:
3p^2
Explanation:
after filling 3s^2 only two electrons left out of 14 so the next sub shell is 3p therefore ,X represents 3p^2
Which statement about entropy is correct? - Entropy is sometimes described as the degree of randomness in a system. - solids are the state of matter with the most entropy. - entropy is a force of nature like gravity. - warm molecules have less entropy then cold molecules.
Answer: Entropy is sometimes described as the degree of randomness in a system.
A 50.0 mL sample of gas at 20.0 atm of pressure is compressed to 40.0 atm of pressure at constant temperature. What is the new volume?
Answer:
20(50) = 40(V₂)
⇒1000 = 40V₂
⇒V₂ = 1000/40
⇒ V₂ = 25 mL
Explanation:
Answer:
25.0 mL
Explanation:
I took the test and got it right :)
Calculate AH for the reaction:
2N2 (g) + 6H20 (g) → 302 (g) + 4NH3(g)
Answer:
Explanation:
4NH₃ (g) + 3O₂ (g) ⇒ 2N₂ (g) + 6H₂ O(1)
Δ[tex]H_r={\sum}{ \Delta }H_f(\text{product})-{\sum}{ \Delta }H_f(\text{reactant})[/tex]
ΔH r =(2ΔH f(N 2 )+6ΔH f (H 2 O(l)))−(4ΔH f (NH 3 (g))+3ΔH f (O 2 (g)))
ΔH rex =[2×0+6×(−286)]−[4×(−46)+3×0]=−1716+186
ΔH rex =−1532kJ/mol
Thermodynamics is a branch of physical chemistry that studies heat and its effects and interactions. Governed by the four main laws, thermodynamics plays a huge role in physics and chemistry, and is also responsible for the law of conservation of energy, a fundamental rule in science.
What is the advantage of using the electromagnetic spectrum model?
It helps compare frequencies of light.
It helps change the wavelengths of light.
The color of light waves can be changed using the model.
The intensities of light waves can be changed using the model.
Answer:
It helps compare frequencies of light.
Explanation: Hope it helps you :)))))
Have a good day.
Answer: A: It helps compare frequencies of light.
Explanation:
What is the mass of butane gas, C4H10, that can be held in a 3.00 L container at STP?
Answer:
3/22.4
Explanation:
Why do Earth and the moon remain in orbit?
Answer:
because of gravitional force(gravity)........
Question 4 of 10
Which statement best describes how scientists and engineers work together
in the research and development cycle?
OA. Scientists develop a theory, and then engineers perform
experiments to verify its accuracy.
B. Engineers do experiments to answer questions about nature, and
then scientists use the results to create a new technology.
OC. Scientists make designs based on engineering knowledge and
then make it available for public use.
D. Engineers develop a new technology, and then scientists use it to
make a new discovery.
Answer: Scientists make designs based on engineering knowledge and
then make it available for public use.
SOUND ENERGY :SCIENCE:
If you have A B C and D 4cups and A has nothing A is control Because the pitch is high but why is it important to have control
Answer:
As the amplitude of the sound wave increases, the intensity of the sound increases. Sounds with higher intensities are perceived to be louder. Relative sound intensities are often given in units named decibels (dB).
Explanation:
A sample of gas is collected in a flask with a volume of 267 mL at a pressure of 771 mmHg and a temperature of 21C. If the mass of the gas is 1.05 g, what is the molar mass of the gas?
Answer:
M=93.5g/mol
Explanation:
I did this in class and it was a review. :)
& Sodium chloride, sugar, starch, and sand are added to water separately in different beakers and the mixtures are stirred well. A suspension will be formed in which case? Give any two reasons for your choice.
Answer:
sugar I like it I think iyrx
A solution of the ionic salt
NaCI would have
pH.
an acidic
a basic
a neutral
Answer:
Neutral
Explanation:
NaCl aqueous solution is formed by NaOH and HCl.
NaOH is a base and HCl is an acid, so they go through neutralization process forming a neutral salt and water.
(b) Glycogen may be broken down to form glucose.
Fig.2.2 shows region X from the glycogen molecule in Fig. 2.1 in more detail.
Draw an annotated diagram in the space provided to explain how a glucose molecule is
formed from the free end of the glycogen molecule shown in Fig.2.2
Glycogen is formed by the loss of water molecules along the length of the polymer chain as the glucose molecules are joined together.
How is glycogen formed?Glycogen is formed by a process known as condensation polymerization. This involves the loss of -OH from one glucose molecule and the loss of H from another glucose molecule as the chain is formed.
Hence, glycogen is formed by the loss of water molecules along the length of the polymer chain as the glucose molecules are joined together.
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Chemistry B Semester Exam
An unknown substance has a boiling point of 174°C. Which statement is true about this unknown substance? (1 point)
-It has a lower boiling point than water, and it likely has stronger electrostatic forces between its molecules
than water.
-It has a higher boiling point than water, and it likely has stronger electrostatic forces between its molecules
than water.
-It has a lower boiling point than water, and it likely has weaker electrostatic forces between its molecules
than water.
-It has a higher boiling point than water, and it likely has weaker electrostatic forces between its molecules
than water.
Answer:
See below
Explanation:
Boiling point of water is 100 C
this substance is higher boiling point and the molecules are likely with higher e-static forces
The unknown substance has a higher boiling point than water, and it has stronger electrostatic forces between its molecules than water. Therefore, option B is correct.
Boiling point is a measure of the temperature at which a substance changes from a liquid to a gas phase. Substances with higher boiling points generally have stronger intermolecular forces, such as hydrogen bonding or stronger dipole-dipole interactions.
Since the boiling point of the unknown substance is higher than that of water (which boils at 100°C), it suggests that the unknown substance likely has stronger electrostatic forces between its molecules compared to water.
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what is called a measurement and does involve a number and unit in chemistry?
Answer:
1.1: Taking Measurements. Chemists measure the properties of matter and express these measurements as quantities. A quantity is an amount of something and consists of a number and a unit. The number tells us how many (or how much), and the unit tells us what the scale of measurement is.
A gas occupies 4.31 liters at a pressure of 0.755 atm. Determine the Temperature
A gas that occupies 4.31 litres at a pressure of 0.755 atm will have a temperature of 39.58°C. Details about temperature can be found below.
How to calculate temperature?The temperature of a gas can be calculated using the following formula:
PV = nRT
Where;
P = pressureV = volumen = number of molesR = gas law constantT = temperature0.755 × 4.31 = 1 × 0.0821 × T
3.25 = 0.0821T
T = 3.25 ÷ 0.0821
T = 39.58°C
Therefore, a gas that occupies 4.31 litres at a pressure of 0.755 atm will have a temperature of 39.58°C.
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