Answer:
THE NUMBER OF MOLES OF HELIUM NEEDED TO FILL A BALLOON AT A VOLUME OF 4.9 L AT 296 K AND 0.78 atm IS 0.00338 moles.
Explanation:
The number of moles is calculated using
PV = nRT
P = Pressure = 0.78 atm
V = volume = 4.9 L
R = gas constant = 0.082 Latm/molK
T = temperature = 296 K
n= number of moles
Substituting theses values and sloving for n, we obtain;
n = PV / RT
n = 0.78 * 4.9 / 0.082 * 296
n = 3.822 / 24.272
n = 0.00338 moles.
So therefore, the number of moles is 0.00338 moles.
Answer:
The number of moles of helium needed is 0.157 moles helium
Explanation:
Step 1: Data given
Volume of the balloon = 4.9 L
Temperature= 296 K
Pressure = 0.78 atm
Step 2: Calculate moles of helium gas
p*V = n*R*T
⇒with p = the pressure = 0.78 atm
⇒with V = the volume = 4.9 L
⇒with n = the number of moles of the helium gas = TO BE DETERMINED
⇒with R = the gas constant = 0.08206 L*atm/mol* K
with T = the temperature = 296 K
n = (p*V) / (R*T)
n = (0.78 atm* 4.9 L) / (0.08206 L*atm/mol*K * 296 K)
n = 0.157 moles of helium
The number of moles of helium needed is 0.157 moles helium
A student conducts an experiment to see how music affects plant growth. The student obtains four identical plants. Each one is potted in the same type of soil and receives the
same amount of sunlight and water each day. Plant A listens to classical music for three hours each day. Plant B listens to rock music for three hours each day. Plant C listens to
country music for three hours each day. Plant D does not listen to any music at all.
2. Based on the experiment in the scenario, which visual aid would be most helpful in showing the change in the plants' heights over time?
O A. A timeline
OB. A line graph
OC. A pie chart
D. A bar graph
Answer:
The type of music each plant listens to.
Explanation:
A variable is any factor or condition whose value is changing in an experiment. A variable can occur in different types or quantity, and three types of variable (independent, dependent, and controlled) can be found in an experiment. In the experiment described above, "the type of music each plant listens to" is the variable. It is an independent variable whose value is changing because it exists in different types and it is the one that the student is observing its effect on the plant’s growth. In this experiment, this variable which differ will also produce different results (or effects).
The temperature of a 350. mL sample of gas increases from 27 °C to 227 °C. What is the final volume of the sample of gas, if the pressure and amount of gas in the container is kept constant?
Group of answer choices
Answer:
[tex]V_2=583.3mL[/tex]
Explanation:
Hello,
In this case, for the given constant amount and pressure of the, we apply the Charles' law which allows us to understand the volume-pressure behavior as a directly proportional relationship:
[tex]\frac{V_1}{T_1} =\frac{V_2}{T_2}[/tex]
Thus, since we need to compute the volume after the temperature increase (which must be expressed in absolute Kelvins), we obtain V2 as:
[tex]V_2=\frac{V_1T_2}{T_1} =\frac{350.0mL*(227+273.15)K}{(27+273.15)K}\\ \\V_2=583.3mL[/tex]
Best regards.
Light brings many chemical changes. Can you think of any chemical change brought about by light?
Answer:
MRCORRECT has answered the question
Explanation:
Film photography is another example ofchemical reaction by light. In this example, the chemical compounds coated on the film go through a chemical reaction. ... These plates (usually made of aluminum) are coated with a photosensitive compound consisting of a polymer and a photosensitivechemical system.
What is a noble gas electron configuration of bismuth?
Answer:
It is [Xe] 4f14 5d10 6s2 6p3 and its atomic number is 83
A reaction starts with 20.0 g of lithium hydroxide (LiOH) and actually produces 31.0 g of lithium chloride (LiCl), what is the percent yield? (Hint: First calculate the theoretical yield of lithium chloride (LiCl))
64.5%
88.6%
81.5%
92.8%
Answer:
87.6 %
Explanation:
Step 1: Write the balanced equation
LiOH + KCl ⇒ LiCl + KOH
Step 2: Calculate the theoretical yield of LiCl
We will use the following relations:
The molar mass of LiOH is 23.95 g/mol.The molar ratio of LiOH to LiCl is 1:1.The molar mass of LiCl is 42.39 g/mol.The theoretical yield of LiCl from 20.0 g of LiOH is:
[tex]20.0gLiOH \times \frac{1molLiOH}{23.95gLiOH} \times \frac{1molLiCl}{1molLiOH} \times \frac{42.39gLiCl}{1molLiCl} = 35.4gLiCl[/tex]
Step 3: Calculate the percent yield of LiCl.
We will use the following expression.
[tex]\%yield = \frac{real\ yield}{theoretical\ yield} \times 100\% = \frac{31.0g}{35.4g} \times 100\% = 87.6 \%[/tex]
Answer:
88.6%
Explanation:
Hello,
In this case, considering the given reaction, we notice a 1:1 molar relationship between lithium hydroxide (molar mass=23.95 g/mol) and lithium chloride (molar mass=42.394 g/mol), for that reason, we are able to compute the theoretical yield of lithium chloride by stoichiometry:
[tex]m_{LiCl}^{theoretical}=20.0gLiOH*\frac{1molLiOH}{23.95gLiOH}*\frac{1molLiCl}{1molLiOH} *\frac{42.394 gLiCl}{1molLiCl}=35.4gLiCl[/tex]
Next, by knowing the actual yield of 31.0 g, we compute the percent yield as:
[tex]Y=\frac{m_{LiCl}^{actual}}{m_{LiCl}^{theoretical}} *100\%=\frac{31.0g}{35.4g}*100\%\\ \\Y=87.6\%[/tex]
Therefore, among the given, the answer should be 88.6%
Best regards.
A compound A (C22H27NO) is insoluble in acid and base but reacts with concentrated aqueous HCl and heat to give a clear aqueous solution from which, on cooling, benzoic acid precipitates. When the supernatant solution is made basic, a liquid B separates. Compound B is achiral. Treatment of B with benzoyl chloride in pyridine gives back A. Evolution of gas is not observed when B is treated with an aqueous solution of NaNO2 and HCl. Treatment of B with excess CH3I, then aqueous Ag2O and heat, gives a compound C, C9H19N, plus styrene, C6H5–CH=CH2. Compound C, when treated with excess CH3I, then aqueous Ag2O and heat, gives a single alkene D that is identical to the compound obtained when cyclohexanone is treated with the ylid –:CH2– PPh3. Give the structure of A.
Answer:
See explaination
Explanation:
Please kindly check attachment for the step by step solution of the given problem
Which shows an isomer of the molecule below?
Answer:
D
Explanation:
An isomer is a molecule with the same number of atoms as another compound, but they differ in arrangement of the atoms.
Answer:
D
Explanation:
A P E X
A 125 g sample of strontium was heated from 0°C to 20°C. It absorbed 750 J of energy. What is the specific heat capacity of iron?
Answer:
Specific heat capacity of iron (C) = 0.3 J/GK
Explanation:
Given:
Mass of sample (m) = 125 gram
Change in heat (ΔT) = 20°C - 0°C = 20°C
Absorbed energy (ΔE) = 750 J
Find:
Specific heat capacity of iron (C) = ?
Computation:
⇒ Specific heat capacity of iron (C) = ΔE / [mΔT]
⇒ Specific heat capacity of iron (C) = 750 / [125 × 20]
⇒ Specific heat capacity of iron (C) = 750 / [2,500]
⇒ Specific heat capacity of iron (C) = 0.3 J/GK
Answer:
Specific heat capacity of iron (C) [tex]= 0.3[/tex] J/g°C
Explanation:
As we know that
Specific heat capacity of iron (C) [tex]=\frac{\delta E}{ [m* \delta T]}[/tex]
Where [tex]\delta E[/tex] represents the change in the energy
m represents the mass of the sample and
[tex]\delta T[/tex] represents the change in temperature.
Given:
Mass of sample (m) [tex]= 125[/tex] gram
Change in heat ([tex]\delta T[/tex] ) [tex]20 - 0 = 20[/tex]
Absorbed energy ([tex]\delta E[/tex])[tex]= 750[/tex] J
Substituting the given values in above equation, we get -
Specific heat capacity of iron (C)
[tex]= \frac{750}{125*20}[/tex]
Specific heat capacity of iron (C) [tex]= 0.3[/tex] J/g°C
) A concentration cell is based on the aqueous reaction
Cu2+(1.00 M) Cu2+(0.0100 M)
The cell consists of copper electrodes dipping into solutions of Cu2+ ions. The anions present are sulfate ions. Draw a neat diagram to represent this cell, showing and labeling all necessary components including: anode, cathode, electron flow, cation flow and anion flow.
Answer:
Kindly check the attachment for the diagram representing the cell and showing all necessary components including: anode, cathode, electron flow, cation flow and anion flow.
Explanation:
So, the reaction in the concentration cell is given below as;
Cu2+(1.00 M) → Cu2+(0.0100 M).--(1).
The anode = Cu2+(0.0100 M) because it has lesser Concentration, thus, lesser potential value.
Cathode = Cu2+(1.00 M) because it has higher Concentration, hence higher potential value.
It must be noted that in the digaram depicting the Reaction, the electrons moves from the anode part of the cell to the cathode part of the cell and this is done through an external circuit. The following are the things that happens at each electrode;
At the Anode: in here is where oxidation occurs and Cu^2+ is released into the solution.
At the cathode: in here is where the reduction occur and the Cu^2+ moves in the direction to where the Cu electrode is, thus, causing the deposition of Cu.
What parts of the body are tested for rigor Mortis
Plants remove carbon to the atmosphere during
Answer:
respiration
Explanation:
Plants give out carbon dioxide not only at night but during the day too. It happens because of the process of respiration in which plants take in oxygen and give out carbon dioxide. As soon as the sun rises another process called photosynthesis starts, in which carbon dioxide is taken in and oxygen is given out.
Plants use photosynthesis to capture carbon dioxide and then release half of it into the atmosphere through respiration. Plants also release oxygen into the atmosphere through photosynthesis
cis-1-Bromo-4-tert-butylcyclohexane and trans-1-bromo-4-tert-butylcyclohexane both react with sodium ethoxide in ethanol to form 4-tert-butylcyclohexene. Explain why the cis isomer reacts much more rapidly than the trans isomer. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.
Answer:
See explanation below
Explanation:
In order to explain this, is neccesary to draw both confomers, the cis and trans, but in the chair conformation, because in that way we can see much better the bonds and the reason of why the cis reacts faster than trans.
As you can see in picture attached, the more stable conformer is the one where the H and Br are in the axial position, and the tert butyl group in equatorial position. In these positions, the cis isomer can undergo an E2 reaction, and the ethoxide would have no problem to substract the hydrogen atom from the molecule to eliminate the Bromide. This is because the t-butyl group in equatorial position, is not exerting steric hindrance, therefore is faster.
In the case of the trans, the t-butyl group is in the axial position as well as the hydrogen and bromide, therefore, when the E2 reaction undergoes, the hydrogen is substracted by ethoxide, but it will be slow because the t.butyl group exerts steric hindrance in the axial positions, therefore, the hydrogen will be substracted slower than in the cis position. This is the main reason for the cis to be faster.
As for the second part of the question, which will be the answer of the whole question, see picture attached 2 for the whole sentence, and the match of the words is the following:
1. Axial
2. More
3. Blank (No word there)
4. less
5. Blank
6. Cis
7. Trans
8. Cis
If you start with 64g of a radioactive element how many half-lives would occur before 8g remain?
Answer:
3 half-lives
Explanation:
The half-life is the time that it takes to a radioactive element to decay to half of its initial amount.
Let's suppose we start with 64 g of the radioactive element.
After 1 half-life, the mass of the element will be 32 g.After 2 half-lives, the mass of the element will be 16 g.After 3 half-lives, the mass of the element will be 8 g.Ascorbic acid (H2C6H6O6), also known as Vitamin C, is a polyprotic acid found in fruit, tomatoes, potatoes and leafy vegetables. The pKa's of the ascorbic acid are pKa1 = 4.10 and pKa2 = 11.80 at 25 °C. When ascorbic acid is titrated with NaOH and it takes 60.0 mL to remove all protons possible. In the titration curve, how many mL of NaOH are required to reach the first pKa? Another way of asking this is when presented with a titration curve of ascorbic acid where on the x-axis should one look (which volume of NaOH), if one wants to determine the first pKa?
Answer:
as when we add 60 ml it removes all the protons it means it is 2nd equivalence point of Ascorbic acid
and we know that pH = pKa1 when moles of NaOH is half of the 1st equivalence point
1st equivalence point = 2nd equivalence point / 2 = 60/2 =30ml
1st half equivalence point = 30/2 = 15ml
so when we add 15ml of NaOH
pH = pKa1 =15mL
If an insufficient amount of liquid unknown had been used, how would this have effected the value of the experimental molar mass
Answer:
Actual yield reduces the more.
Explanation:
An actual yield of the course of a chemical reaction is the mass of a product actually obtained from the reaction.
In practice you see it and It is usually less than the theoretical yield.
Various reasons may come up to explain this away but here is one:
• incomplete reactions, simply put here some of the reactants do not react to form the product.
The same applies in the question about the actual yield will reduce significantly in molar mass now that insufficient amount of reagent are used.
A certain element X has four isotopes. 5.845% of X has a mass of 53.93961 amu. 91.75% of X has a mass of 55.93494 amu. 2.123% of X has a mass of 56.93539 amu. 0.2820% of X has a mass of 57.93328 amu. What is the average atomic mass of element X? Express your answer numerically to four significant figures.
Answer:
Average atomic mass of element X is 56.19 amu
Explanation:
Given:
Four isotopes of X:
5.845% of X has a mass of 53.93961 amu.
91.75% of X has a mass of 55.93494 amu.
2.123% of X has a mass of 56.93539 amu.
0.2820% of X has a mass of 57.93328 amu.
To find: average atomic mass of element X
Solution:
Isotopes are variants of a particular chemical element such that they have the same number of protons but different number of neutrons.
Average atomic mass of element X = [tex]\frac{53.93961+55.93494+56.93539+57.93328}{4}=\frac{224.74322}{4}=56.185805\approx 56.19[/tex]
So, the average atomic mass of element X is 56.19 amu.
A polymer coating of 6:0 mm thickness is cast onto a nonporous flat surface. The coating contains a residual amount of casting solvent, which is uniform at 1.0 wt% within the coating. The mass transfer of solvent through the polymer coating is controlled by molecular diffusion. The air flowing over the coating surface eliminates convective mass-transfer resistances and reduces the solvent vapor concentration in the air to nearly zero. The effective diffusion coefficient of the solvent molecules in the polymer is 2 x 10^-6 cm^2/s.
a. How many hours will it take for the solvent concentration at 1.2 mm from the surface to be reduced to 0.035 wt%?
Answer:
vent vapor concentration in the air to nearly zero. The effective diffusion coefficient of the solvent molecules in the polymer is 2 x 10^-6 cm^2/s
Explanation:
In a titration, 100 mL of 0.026 M HCl (aq) is neutralized by 13 mL of KOH(aq). Calculate the molarity of KOH (aq).
Answer:
0.2M
Explanation:
Step 1:
Data obtained from the question.
Volume of acid (Va) = 100mL
Molarity of the acid (Ma) = 0.026 M
Volume of base (Vb) = 13mL
Molarity of the base (Mb) =..?
Step 2:
The balanced equation for the reaction. This is given below:
HCl + KOH —> KCl + H2O
From the balanced equation above,
The mole ratio of the acid (nA) = 1
The mole ratio of the base (nB) = 1
Step 3:
Determination of the molarity of the base, KOH. This can be obtained as follow:
MaVa/MbVb = nA/nB
0.026 x100 / Mb x 13 = 1
Cross multiply to express in linear form
Mb x 13 = 0.026 x 100
Divide both side by 13
Mb = 0.026 x 100 / 13
Mb = 0.2M
Therefore, the molarity of the base, KOH is 0.2M
Answer:
0.2M
Explanation:
KOH(aq) + HCl(aq) ⇒ KCl(aq) + H2O(l)
We express the moles of analyte (HCl) and titrant based (KOH) on their molar concentration:
M1 * V1 = M2 * V2
The molarity of the solution is calculated with the following equation:
M2 = V1 x M1 / V2
Where:
V2 = valued sample volume
V1 = volume of titrant consumed (measured with the burette)
M1 = concentration of titrant solution
M2 = concentration of sample
M2 = 100mL * 0.026M / 13mL = 0.2M
6. Find the partial pressures of the gases in a mixture with a total pressure of 101.3 kPa, if there are 7.8 mole of
Ng, 2.1 mole of 0, 0.090 mole of Ar, and 0.010 mol of Co,
3:20
5/10/2
19
110
112
Pause
break
16
X
14
&
*
A
%
7
9
5
6
O
8
4
{
о
Р
Answer:
Explanation:
Total mole of gases = 7.8 + 2.1 + .09 + .01 = 10
the partial pressures of the gases in a mixture
= mole fraction x Total pressure
mole fraction = mole of a gas in the mixture / total mole
partial pressure of Ng = [tex]\frac{7.8}{10} \times 101.3 kPa[/tex]
= 79.014 kPa
partial pressure of O = [tex]\frac{2.1}{10} \times 101.3 kPa[/tex]
= 21.273 kPa .
partial pressure of Ar = [tex]\frac{.09}{10} \times 101.3 kPa[/tex]
= .9117 kPa .
partial pressure of Co = [tex]\frac{.01}{10} \times 101.3 kPa[/tex]
= .1013 k Pa .
How do you calculate the number of protons, neutrons, and electrons in an element?
Answer:
The first thing you will need to do is find some information about your element. Go to the Periodic Table of Elements and click on your element. If it makes things easier, you can select your element from an alphabetical listing.
Number of Protons = Atomic Number
Number of Electrons = Number of Protons = Atomic Number
Number of Neutrons = Mass Number - Atomic Number
For krypton:
Number of Protons = Atomic Number = 36
Number of Electrons = Number of Protons = Atomic Number = 36
Number of Neutrons = Mass Number - Atomic Number = 84 - 36 = 48
Explanation:
hope this helps, have a good day :-)
If the mole fraction of Na2S in an aqueous solution is 0.125,
what is the weight/weight %
(percent by mass) of Na2S?
Answer:
Explanation:
Hello,
In this case the molar fraction of sodium sulfide, whose molar mass is 78 g/mol, is 0.125, it means we have 0.125 moles of sodium sulfide per mole of solution, so we compute the mass of sodium sulfide and water as shown below:
[tex]m_{Na_2S}=0.125mol*\frac{78gNa_2S}{1molNa_2S} =9.75 gNa_2S\\\\m_{H_2O}=(1-0.125)molH_2O*\frac{18gH_2O}{1molH_2O} =15.75gH_2O[/tex]
Then, we can calculate the eight/weight % as follows:
[tex]w/w \%=\frac{9.75g}{9.75g+15.75g}*100\% \\\\w/w \%=38\%[/tex]
Regards.
Answer: 38
Explanation:
Nitrogen gas was collected by water displacement. What was the pressure of the N2 collected if the temperature was 50 degrees celcius?
Answer:
Explanation:
Atmospheric pressure = 101.325 kPa
vapor pressure of water at 50°C = 12.332 kPa
pressure of N₂ = (Atmospheric pressure) - (vapor pressure of water at 50 oC)
pressure of N₂ = (101.325 kPa) - (12.332 kPa)
pressure of N₂ = 88.993 kPa
Therefore, the pressure of the N₂ collected if the temperature was 50 degrees celcius is 88.993 kPa40 POINTS!
Answer correctly for full 40!
Answer:
A. cell wall
Explanation:
A cell wall is rigid and is the outermost layer. It also shapes the cell.
A cell membrane is the inner portion of the cell wall and very flexible, not rigid.
The nucleus is not a membrane, it is the center of cell containing genetic information.
The mitochondria is within the cell and it known as the "powerhouse" of the cell.
- Hope that helps! Please let me know if you need further explanation.
Answer:
Jesus loves you
Which pigment is responsible for grey hair?
A
Eumelanin
В
Pheomelanin
с
Both Eumelanin and Pheomelanin
D
No pigment
3 of 10
Answer:
No pigment.
Explanation:
Pigment makes color, and hair loses color when it loses pigment.
A chemist wants to increase the solubility of a solid in water. Which of the
following will NOT help? *
-increase the temperature
-decrease the particle size
-Increase stirring
-increase pressure
Answer:
- Increase pressure .
Explanation:
Hello,
In this case, during the dissolution process, the solute's molecules rearrange in order to get together with the solvent's molecules, in this case water.
Now, since we are talking about a solid whose particles are intimately held together, the only way to separate them is by increasing the temperature because the molecules start moving so they can join water's molecules, decreasing particle size since they will be more likely to separate to each other and increasing stirring since the applied energy will break the solid's intramolecular forces.
In such a way, since pressure significantly affects gases and slightly affects liquid, it is not able to modify a solid, just extreme pressures such as it needed to produce diamonds, is able to affect a solid. For that reason, increasing the pressure will not increase the solid's solubility.
Best regards.
please help! BRAINLIEST to right answerrrr
Answer: from the hotter surface to the colder one
Explanation:
Answer:d
d
Explanation:
The image shows two different species. the image is a dog and a lizered
Which is a shared characteristic of these two species?
tail
scales
hair
body shape
Answer:
the tail
Explanation:
Answer:
A.) tails
Explanation:
A student wants to examine a substance without changing its identity. Which of the following properties should the student examine?
Answer:
A. Ductility, because it can be observed by altering the shape of the substance
Explanation:
Changing the shape of a substance does not change its identity.
What are 3 stages of the water cycle are
After 56.0 min, 40.0% of a compound has decomposed. What is the half‑life of this reaction assuming first‑order kinetics?
Answer:
Go ahead and plug in the percentages and time to find the answer.
Explanation:
The amount of a substance with half-life h, that remains after time t is 0.5t/h
Since 26% has decomposed, 74% remains.
So .74 = 0.580/h
ln .74 = (80/h) ln 0.5
h/80 = ln 0.5 / ln .74
h = 80 ln 0.5 / ln .74
h = 184.16 minutes
