What is the work function of gold metal in kJ/mol if light with λ = 234 nm is necessary to eject electrons?
Answer
512kj/mole
Explanation:
What is the work function of gold metal in kJ/mol if light with λ = 234 nm is necessary to eject electrons?
The energy can be calculated using below expresion;
E = hc/λ
Where h= planks constant= 6.626 x 10^-34
c= speed of light= 3 x 10^
λ= wavelength
hc= (6.626 x 10^-34 x 3 x 10^ 8)
=
What is the mass of the oxygen in one mole of calcium phosphate
Answer:
16.00 g/mol
Explanation:
Answer:
16.00 g/mol
Explination:
1 mol of calcium phosphate contains 8 moles of oxygen. From this, we can compute for the amount of oxygen in grams using the molar mass of oxygen, which is 16.00 g/mol.
What branch of science studies The Periodic Table?
A.Biology
B.Earth Science
Chemistry
Atoms mover slower in the ____________. *
A.heat
B.cold
Atoms move faster in the __________. *
A.heat
B.cold
A nucleus is made of ________ and _________. *
A.protons and electrons
B.electrons and neutrons
C.protons and neutrons
Protons have what type of charge? *
A.neutral
B.negative
C.positive
Neutrons have what type of charge? *
A.neutral
B.negative
C.positive
Atoms have empty space. *
A.True
B.False
What is the center of an atom called? *
A.Neutron
B.Nitrogen
C.Nucleus
The atomic number represents the number of _______. *
A.protons
B.neutrons
C.electrons
What family of elements is most stable? *
A.metals
B.nonmetals
C.Nobel gasses
What scientist is credited with designing The Periodic Table? *
A.Albert Einstein
B.Isaac Newton
C.Dmitri Mendeleev
Atomic mass is found at the _______________.
A.top of the square
B.the middle of the square
C.the bottom of the square
The Periodic Table has elements that are liquids, gasses, and solids. *
A.True
B.False
With an atomic number of 1, which element is the lightest? *
A.Helium
B.Xenon
C.Hydrogen
D.Radon
Answers:
1. Chemistry
2. Cold
3. Heat
4. Protons and neutrons
5. Positive
6. Neutral
7. True
8. Nucleus
9. Protons
10. Nobel gasses
11. Dmitri Mendeleev
12. the bottom of the square
13. True
14. Helium
How does evidence of chemical
reactions indicate that new substances
with different properties are formed?
Answer:
Changes in Properties Changes in properties result when new substances form. For instance, gas production, formation of a precipitate, and a color change are all possible evidence that a chemical reaction has taken place. ... Change in Color A color change can signal that a new substance has formed.
Explanation:
The chemical reaction indicate the formation of new substance by change in nature of original compound and shows chemical changes in the reaction.
What is chemical reaction?Chemical reaction is defined as process in which two or more molecules collide with the proper orientation and enough force to produce a new product.
It is also defined as a procedure in which one or more compounds, known as reactants, are changed into one or more distinct substances, known as products.
There are mainly seven types of reaction.
Synthesis reactionDecomposition reactionDisplacement reactionDouble displacement reactionCombustion reactionRedox reactionAcid-Base reactionThus, the chemical reaction indicate the formation of new substance by change in nature of original compound and shows chemical changes in the reaction.
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A student writes Ba?- as the symbol for a barium ion. Explain what is incorrect about the symbol.
Answer:
ion is missing
Explanation:
how do you determine number of valence electrons an element has
Answer:the first column has one valance electron the second has 2 and so on.
The only exception is helium that has 2.
Explanation:
While performing a neutralization reaction, Jonna added 22.63 mL of 0.142 M H2SO4 to 46.21 mL of 0.304 M KOH. How many moles of OH- are unreacted in the solution after the neutralization is complete?
Answer:
7.623 x 10⁻³ mol OH⁻
Explanation:
The reaction that takes place is:
H₂SO₄ + 2KOH → K₂SO₄ + 2H₂ONow we calculate how many moles of each reagent were added:
H₂SO₄ ⇒ 22.63 mL * 0.142 M = 3.213 mmol H₂SO₄KOH ⇒ 46.21 mL * 0.304 M = 14.05 mmol KOHWe calculate how many OH⁻ moles reacted with H₂SO₄:
3.213 mmol H₂SO₄ * [tex]\frac{2mmolOH^-}{1mmolH_2SO_4}[/tex] = 6.427 mmol OH⁻Finally we substract the OH⁻ moles that reacted from the added ammount of OH⁻ moles:
14.05 mmol KOH - 6.427 mmol OH⁻ = 7.623 mmol OH⁻7.623 mmol / 1000 = 7.623 x 10⁻³ mol OH⁻The number of moles of OH⁻ that are unreacted in the solution after the neutralization reaction is complete is 0.00770 moles OR 7.70×10⁻³ moles
First, we will write a balanced chemical equation for the neutralization reaction
The balanced chemical equation for the neutralization reaction is
H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O
This means
1 mole of H₂SO₄ reacts with 2 moles of KOH to give 1 mole of K₂SO₄ and 2 moles of H₂O
To determine the number of moles of OH⁻ that are unreacted after the neutralization is complete,
We will determine the number of moles of KOH remaining in the solution after the neutralization reaction is complete
First, we will determine the number of moles of each reactant present
For H₂SO₄Volume = 22.36 mL = 0.02236 L
Concentration = 0.142 M
From the formula,
Number of moles = Concentration × Volume
∴ Number of moles of H₂SO₄ = 0.142 × 0.02236
Number of moles of H₂SO₄ = 0.00317512 moles
For KOHVolume = 46.21 mL = 0.04621 L
Concentration = 0.304 M
∴ Number of moles of KOH = 0.304 × 0.04621
Number of moles of KOH = 0.01404784 moles
(NOTE: This is equal to the number of moles of OH⁻ at the beginning of the reaction)
From the equation of reaction, we have that
1 mole of H₂SO₄ will neutralize 2 moles KOH
Therefore,
0.00317512 moles of H₂SO₄ will neutralize 2×0.00317512 moles KOH
2×0.00317512 = 0.00635024 moles
This means only 0.00635024 moles of KOH reacted
(NOTE: This is equal to the number of moles of OH⁻ that reacted)
Now, for the number of moles of unreacted OH⁻
Number of moles of unreacted OH⁻ = Total number of moles OH⁻ at the beginning of the reaction - Number of moles of OH⁻ that reacted
∴ Number of moles of unreacted OH⁻ = 0.01404784 moles - 0.00635024 moles
Number of moles of unreacted OH⁻ = 0.0076976 moles
Number of moles of unreacted OH⁻ ≅ 0.00770 moles OR 7.70×10⁻³ moles
Hence, the number of moles of OH⁻ that are unreacted in the solution after the neutralization is complete is 0.00770 moles OR 7.70×10⁻³ moles
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If a horse travels 20 meters in 5 seconds what is the horses speed
distance = speed * time
speed = distance / time
speed = 20 meters / 5 seconds
speed = 4 meters / second
hope this helped!
According to the following reaction, how many grams of sulfur are formed when 37.4 g of water are formed?
2H₂S(g) + SO₂(g) → 3S(s) + 2H₂O(l)
Answer:
Mass = 100.8 g
Explanation:
Given data:
Mass of sulfur formed = ?
Mass of water formed = 37.4 g
Solution:
Chemical equation:
2H₂S + SO₂ → 3S + 2H₂O
Number of moles of water:
Number of moles = mass/molar mass
Number of moles = 37.4 g/ 18 g/mol
Number of moles = 2.1 mol
Now we will compare the moles of water and sulfur.
H₂O : S
2 : 3
2.1 : 3/2×2.1 = 3.15
Mass of sulfur:
Mass = number of moles × molar mass
Mass = 3.15 mol × 32 g/mol
Mass = 100.8 g
Which of the following is NOT a property of gases?
Your answer:
A.They are easy to compress.
B.They expand to fill their containers.
C.They have a definite shape and a definite volume.
D.They occupy far more space than the liquids or solids from which they form.
Answer: C
Explanation:
A. As they do not have a given shape and expand to fill the container, modifying the size of the container modifies the space the gas occupies
B. They are nearly free molecules, which means no bound between them, moving fast and freely around the container
C. NOT A PROPERTY. As said before, as there are no bindings between molecules and move freely, they cannot have a fixed size cause they're always on the move.
D. Because they expand to fill the container, it's easy to them to occupy more space than in any other state, as the container is the only thing that defines how much volume they occupy
Give the location in the Periodic Table of Elements that have the same number of electron shells
all columns (groups) have the same number of shells
all periods (rows) have the same number of shells
only the transition metal elements have the same number of shells
Group VIII
Explanation:
All period have the same number of shells
can someone put this in other words Conduct an investigation to explore the use of Punnett squares to predict genotypes and phenotypes of offspring.
Help ASAP
Please and thank you
Answer: C
Explanation: Everything else is true.
Which of the following elements has the heaviest atom?
a. nickel
b. lead
c. iron
d. gold
Answer:
IronExplanation:
Because it is never because iron weights 9 tons or 17,000 poundsAnswer:
b. lead
Explanation:
look on the periodic table and it has its atomic mass and lead (Pb) is the heaviest
Which element has the lowest first ionization energy?
NEED ASAP
Select one:
a. 1s22s22p63s23p5
b. 1s22s1
c. 1s22s22p63s23p6
d. 1s22s22p63s1
Answer:
C
Explanation:
there is no explanation needed
Answer:
The value of ionization energy (IE) decreases down the group due to the increasing size as the valence electrons are more loosely bound. Thus lowest IE in this case is of Bi as it is bottom most element.
Explanation:
Select the best answer from the choice below. When the wavelength decreases, the frequency:
Answer:
Increases
Explanation:
Frequency and wavelength of lights are inversely proportional to each other.
The wave of light having highest frequency have shortest wavelength and the light with the shortest frequency having highest wavelength.
Formula:
Speed of light = wavelength × frequency
c = λ × f
λ = c/f
This formula shows that both are inversely related to each other.
The speed of light is 3×10⁸ m/s
Frequency is taken in Hz.
It is the number of oscillations, wave of light make in one second.
Wavelength is designated as "λ" and it is the measured in meter. It is the distance between the two crust of two trough.
Calculate the maximum mass of a metal, with equivalent mass of 20 g, that should be used in an equivalent mass determination with a 100-mL eudometer tube for collection. For the purposes of calculation, assume 80 mL of hydrogen gas produced at standard conditions. (Round to 2 sig figs)
Answer:
Explanation:
In the equivalent mass measurement , one gram equivalent of metal produces 11200 mL of hydrogen gas .
11200 mL hydrogen gas is produced by 1 gram equivalent of gas at STP
11200 mL hydrogen gas is produced by 20 g of gas at STP
80 mL hydrogen gas is produced by 20 x 80 / 11200 g of gas at STP
= 142.85 mg .
= 140 mg . ( rounded to 2 sig figures )
Ammonium phosphate NH43PO4 is an important ingredient in many solid fertilizers. It can be made by reacting aqueous phosphoric acid H3PO4 with liquid ammonia. Calculate the moles of ammonium phosphate produced by the reaction of 2.3mol of ammonia. Be sure your answer has a unit symbol, if necessary, and round it to the correct number of significant digits.
Answer:
0.767 moles of ammonium phosphate are produced
Explanation:
The reaction of ammona (NH3), with phosphoric acid is:
3 NH3 + H3PO4 → (NH4)3PO4
Where 3 moles of ammonia reacts per mole of H3PO4 to produce 1 mole of ammonium phosphate.
If 2.3 moles of ammonia reacts, the moles of ammonium phosphate produced if phosphoric acid is in excess are:
2.3 moles NH3 * (1 mole (NH4)3PO4 / 3 moles NH3) =
0.767 moles of ammonium phosphate are produced
If the temperature of the water inside of the
pressure cooker is greater than 104'C, and the
water is still a liquid, then the pressure inside of the
pressure cooker must be
less than 1 atm
equal to 1 atm
c.
greater than 1 atm
Answer:
(C). Greater than 1atm
Explanation:
We are aware that water boils at 100 degree Celsius. Water can change its phase and become vapor at 100degree Celsius and at normal pressure which is 1atm.
In the given scenario we have enough temperature to convert water into vapor phase but we don't want it rather we want it to remain in liquid state. This can be achieved by increasing the pressure which was earlier required for vapor phase conversion. So the pressure should be greater than 1atm.
When we increase the temperature the molecules will get enough energy to escape into vapor phase, but when we will increase the pressure, it will provide hindrance to those molecules and will maintain them into Liquid state.
Chlorophyll is found in
A. neither plant
nor animal cells.
B. animal cells.
C. plant cells.
D. plant and animal cells.
Answer:
Only plant cells
Explanation:
This organelle helps plants photosynthesize. Humans do not do that.
If 15.5 mL of 0.225 M aqueous magnesium chloride is added to 37.5 mL of 0.250 M aqueous lead(II) nitrate, then what mass of lead(II) chloride precipitates?A. 0.485 g.B. 0.971 g.C. 1.94 g.D. 3.888 g.E. 5.82 8 g.
Answer:
B. 0.971 g
Explanation:
When MgCl₂(aq) reacts with Pb(NO₃)₂(aq), PbCl₂(s) and Mg(NO₃)₂(aq) are produced:
MgCl₂(aq) + Pb(NO₃)₂(aq) →, PbCl₂(s) + Mg(NO₃)₂(aq)
Thus, we need to find imiting reactant finding moles of each reactant:
Moles MgCl₂:
15.5mL = 0.0155L * (0.225 mol / L) = 3.49x10⁻³ moles
Moles Pb(NO₃)₂:
37.5mL = 0.0375L * (0.250mol / L) = 9.38x10⁻³ moles
As the ratio of the reactants is 1:1, the moles of PbCl₂ are 3.48x10⁻³ moles.
We need to convert thes moles to mass using molar mass of PbCl₂ (278.1g/mol), thus:
3.48x10⁻³ moles * (278.1g/mol) =
0.968g of PbCl₂ are precipitate
Thus, right answer is:
B. 0.971 gplz help ❤️
Explain how the pH of water has a synergistic relationship with other substances.
Provide an example.
Answer:
Explanation:
he pH of the water will determine the toxic effects, if any, of these substances.
Pure water is neutral with the pH of 7. But when water combines with other substance the pH varies as per the acidity of the combining substance.
What is pH?pH is the measure of acidity of a solution and mathematically it is the negative logarithm of hydrogen ion concentration. Acidic substance have a pH of less than 7 whereas, basic substance have higher pH value.
Water when combines with some acids, its acidity increases. For example acid rain resulting from the reaction of rain water with oxides of nitrogen and Sulphur forming nitric acid and sulphuric acid.
pH of water have a role in the toxic effects of components in water pH and alkalinity of water determines the coagulation of other substances in water.
Hence, the properties of other substance in water is pH dependent and might effect the alkalinity or acidity of water as well the properties of substances in water such as toxicity.
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**I WILL PAY MONEY** i have 10 pages in a chemistry packet mostly multiple choice, whoever could do them for me i can pay like 20$. it would mean a lot. i attached pictures of what its like
Answer:
Ill do it for free hmu on Insta (allmyhomiesbeautiful) or Snap (nzmbndzmb)
What is the atomic mass of aluminum?
Help ASAP!!!! Already got a D in that class subject is science but that’s the closed I can get
Answer:
26.982
Explanation:
Use the periodic table
What is the concentration of chloride ions in a solution that contains 0.375 g of aluminum chloride in 15.0 mL of solution?
Answer:
0.561 M
Explanation:
Step 1: Given data
Mass of aluminum chloride (m): 0.375 gMolar mass of aluminum chloride (M): 133.34 g/molVolume of the solution (V): 15.0 mLStep 2: Calculate the molar concentration of aluminum chloride (C)
We will use the following expression.
[tex]C = \frac{m}{M \times V(L) } = \frac{0.375g}{133.34 g/mol \times 0.0150L } = 0.187M[/tex]
Step 3: Write the reaction of dissociation of aluminum chloride
AlCl₃(aq) ⇒ Al³⁺(aq) + 3 Cl⁻(aq)
Step 4: Calculate the concentration of chloride ions
The molar ratio of AlCl₃ to Cl⁻ is 1:3. The concentration of Cl⁻ is 3/1 × 0.187 M = 0.561 M
Liquid nitrogen is kept at a temperature of -320 degrees. When liquid nitrogen is heated it quickly boils and turns into a gas. Which pair of pictures represent the change caused by adding heat to liquid nitrogen?
So when something is boiling it is moving faster meaning the molecules are more spread out and not condense like a solid
So the answer is the 2nd set
15.0 moles of gas are in a 8.00 L tank at 22.3 ∘C∘C . Calculate the difference in pressure between methane and an ideal gas under these conditions. The van der Waals constants for methane are a=2.300L2⋅atm/mol2 a=2.300L2⋅atm/mol2 and b=0.0430L/molb=0.0430L/mol.
Answer:
[tex]\Delta P=4.10atm[/tex]
Explanation:
Hello!
In this case, since the ideal gas equation is used under the assumption of no interaction between molecules and perfectly sphere-shaped molecules but the van der Waals equation actually includes those effects, we can compute each pressure as shown below, considering the temperature in kelvins (22.3+273.15=295.45K):
[tex]P^{ideal}=\frac{nRT}{V}=\frac{15.0mol*0.08206\frac{atm*L}{mol*K}*295.45K}{8.00L}=45.5atm[/tex]
Next, since the VdW equation requires the molar volume, we proceed as shown below:
[tex]v=\frac{8.00L}{15.0mol}=0.533\frac{L}{mol}[/tex]
Now, we use its definition:
[tex]P^{VdW}=\frac{RT}{v-b} -\frac{a}{v^2}[/tex]
Thus, by plugging in we obtain:
[tex]P^{VdW}=\frac{0.08206\frac{atm*L}{mol*K}*295.45K}{0.533mol/L-0.0430L/mol} -\frac{2.300L^2*atm/mol^2}{(0.533L/mol)^2}\\\\P^{VdW}=49.44atm-8.09atm\\\\P^{VdW}=41.4atm[/tex]
Thus, the pressure difference is:
[tex]\Delta P=45.5atm-41.4atm\\\\\Delta P=4.10atm[/tex]
Best regards!
if a student added water to her cola what change would you expect to see in the ph level
Answer:
You would expect it to go down
Explanation:
This is because she is essentially watering down, causing the Ph level to go down too.
If a student added water to her cola, then the pH level is low. This is due to the fact that she is essentially diluting, which lowers the pH level as well.
What is pH ?The pH scale determines how acidic or basic water is. The range is 0 to 14, with 7 representing neutrality. Acidity is indicated by pH values below 7, whereas baseness is shown by pH values above 7. In reality, pH is a measurement of the proportion of free hydrogen and hydroxyl ions in water.
pH stands for "Potential of Hydrogen" in its full form. The negative logarithm of the concentration of H+ ions is known as pH. As a result, the meaning of pH is defined as the strength or power of hydrogen.
A solution's pH is a significant indicator of its chemical composition. The pH can affect how readily available nutrients are, how biological processes work, how bacteria behave, and how chemicals behave.
Thus, If a student added water to her cola, then the pH level is low.
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If you wanted to change the polarity of hydrogen bromide (HBr) by substituting the bromine with a different atom. Which atom would increase the polarity of the molecule?
Answer:
This question is incomplete as it lacks options, the options are:
A. chlorine (CI)
B. iodine (1)
C. sulfur (S)
D. hydrogen (H)
The answer is A. Chlorine
Explanation:
Polarity of a substance in chemistry is a function of electric charges in the atoms of the molecules involved. Polarity, however, can be increased or decreased in molecules depending on the charges of the atoms that form them.
Since polarity increases when an atom in the molecule has a high ability to pull electrons toward itself i.e. electronegativity, one atom that can be substituted for Bromine in the hydrogen bromide (HBr) molecule in order to increase its polarity is CHLORINE. This is because Chlorine (Cl) is more electronegative than Bromine atom, hence, will pull more electrons from hydrogen to make the HCl molecule more polar than HBr.
To increase the polarity of HBr, the bromine atom can be replaced with a hydrogen atom.
A polar molecule is one in which a dipole moment exists. There is a positive end and a negative end in a polar molecule. Conventionally, the direction of the dipole is from the positive end of the molecule towards the negative end of the molecule.
If we want to increase the polarity of the molecule then we must substitute the bromine atom with a more electronegative atom. In this case, chlorine is the best option.
Missing parts;
If you wanted to change the polarity of hydrogen bromide (HBr) by substituting the bromine by a different atom. Which atom would increase the polarity of the molecule?
A. chlorine (CI)
B. iodine (1)
C. sulfur (S)
D. hydrogen (H)
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What type of change is sugar dissolving in water physical or chemical
Answer:
Physical
Explanation:
No new substance is formed.
The process can be reversed using evaporation to separate the sugar from the water
So the change is physical
Hope this helps :)