Complete Question
You and your lab partner are asked to determine the density of an aluminum bar. The mass is known accurately (to four significant figures). You use a simple metric ruler to measure its dimensions and obtain the results for Method A. Your partner uses a precision micrometer and obtains the results for Method B.
Method A (g/cm3) 2.2,2.3,2.7,2.4 Method B (g/cm3) 2.703 2.701 2.705 5.811
The accepted density of aluminum is 2.702 g/cm 3 .
(a) Calculate the average density for each method.
Should all the experimental results be included in your calculations? If not, justify any omissions.
(b) Calculate the percent error for each method’s average value.
(c) Calculate the standard deviation for each set of data.
(d) Which method’s average value is more precise? Which method is more accurate?
Answer:
a)[tex]Ma_{avg}= 2.4g/cm^3[/tex]
[tex]Mb_{avg}=2701g/cm^3[/tex]
b)[tex]PE_a=7.5\%[/tex]
[tex]P.E_b=28.8 \%[/tex]
c) [tex]\sigma_A=0.35[/tex]
[tex]\sigma_B=0.0545[/tex]
d)Method A
Explanation:
From the question we are told that:
Method A Density values
2.7
Method B Density values
2.703,2.701,2.705,5.811
Density of aluminium [tex]p_d=2.702 g/cm^3[/tex].
a)
Generally the average density for each method is mathematically given by
Method A
[tex]Ma_{avg}= \frac{2.2+2.3+2.7+2.4}{4}[/tex]
[tex]Ma_{avg}= 2.4g/cm^3[/tex]
Method B
[tex]Mb_{avg}=\frac{2.703+2.701+2.705}{3}[/tex]
[tex]Mb_{avg}=2701g/cm^3[/tex]
b)
Generally the equation for percentage error [tex]PE[/tex] is is mathematically given by
percent error = (measured- real)/real *100
Given real = 2.702 g/ cm3
Method A =
[tex]PE_a=(2.5- 2.702)* \frac{100}{2.702}[/tex]
[tex]PE_a=7.5\%[/tex]
Method B =
[tex]PE_b=( 3.481- 2.702)*\frac{100}{2.702}[/tex]
[tex]P.E_b=28.8 \%[/tex]
c)
Generally the standard deviation [tex]\sigma[/tex] for each method is mathematically given by
Method A
[tex]\sigma=\sqrt{\frac{\sum(x-a)^2}{N} }[/tex]
[tex]\sigma=\sqrt{\frac{0.25+0.16+0+0.09}{4} }[/tex]
[tex]\sigma_A=0.35[/tex]
Method B
[tex]\sigma=\sqrt{\frac{\sum(x-a)^2}{N} }[/tex]
[tex]\sigma=\sqrt{\frac{0.000001+0.00000+0.000009+0.011881}{4} }[/tex]
[tex]\sigma_B=0.0545[/tex]
d)
Therefore with lower percentage error the method who's average value is more precise is
Method A
how many atoms of carbon are in a diamond with a mass of 0.568 g?
Answer:
There are 2.85 x 10^22 atoms of carbon in a diamond with a mass of 0.568 g.
Hope this helps! :)
LEVEL 3
Write the correct order
of letters to the finish line.
A E B E C
Example:
ABCGH
G
H
N
eza
Not correct
How many grams (g) are in 4.00 moles of Carbon (C) ?
Answer:
There are 36 grams in 4.00 moles of Carbon.
Explanation:
In order to convert from moles of a substance into grams of the same substance, we need to use the substance's molar mass.
That means that in this case we use the molar mass of Carbon:
4.00 mol * 12 g/mol = 36 gThus, there are 36 grams in 4.00 moles of Carbon.
Question 6 of 10
What could make AG become negative at a given enthalpy and entropy?
A. Changing the temperature
B. Changing the concentrations
C. Changing the pressure
D. Changing the volume
SUBMIT
Answer:
A via A P E X
The entity that would make ΔG to become negative at a given enthalpy and entropy is Changing the temperature (Option A)
Gibbs free energyΔG = ΔH – TΔS
Where
ΔG is the Gibbs free energy ΔH is the enthalpy changeT is the temperature ΔS is the change in entropyNOTE
ΔG = +ve (non spontaneous)
ΔG = 0 (equilibrium)
ΔG = –ve (spontaneous)
From the Gibbs free energy equation, we can see that the entities that makes us the equation are
Enthalpy, ΔHEntropy, ΔSTemperature, TThus, we can conclude that the correct answer to the question is: changing the temperature (Option A) since the equation has nothing to do with neither concentration, pressure nor volume
Learn more about Gibbs free energy:
https://brainly.com/question/9552459
#SPJ2
d. If you were to open the carbonated drink bottle after shaking, what would you expect to happen and why? If you were to open the water bottle after shaking, what would you expect to happen and why?
Shaking causes small bubbles, which helps the soda's carbon dioxide escape faster. The gas will gradually escape from the liquid as bubbles once the can is opened, and the soda will become "flat." The dissolved gas takes a long time to escape if the liquid is treated gently.
How to find the net ionic of an equation
Select the correct answer.
For Al, its atomic number is 13 and its mass number is 27. How many neutrons does it have?
Ο Α. .
13
ОВ.
14
26
OD
27
O E
40
Answer:
B.) 14
Explanation:
27-13=14 neutrons
Match each definition to the appropriate term.
a. The condition that a reaction takes place without outside help _________
b. Difference of the enthalpy (of a system) minus the product of the entropy and absolute temperature ________
c. Sum of the internal energy plus the product of the pressure and volume for a reaction _________
d. The extent of randomness in a system __________
e. Solution in which no more solute can be dissolved in the solven ________
1. Gibbs free energy
2. Spontaneity
3. Saturated solution
4. Entropy
5. Enthalpy
Answer:
a. The condition that a reaction takes place without outside help Spontaneity
b. Difference of the enthalpy (of a system) minus the product of the entropy and absolute temperature Gibbs free energy
c. Sum of the internal energy plus the product of the pressure and volume for a reaction Enthalpy.
d. The extent of randomness in a system Entropy
e. Solution in which no more solute can be dissolved in the solven Saturated solution
Explanation:
(a) SPONTANEITY - The quality of being natural rather than planned in advance is described as spontaneity.
(b) GIBBS FREE ENERGY - Gibbs free energy, also known as the Gibbs function, Gibbs energy, or free enthalpy, is a quantity used to quantify the maximum amount of work that can be performed in a thermodynamic system when the temperature and pressure are held constant. The symbol ‘G' stands for Gibbs free energy.
(c) ENTHALPY - The heat absorbed or released during a process at constant pressure is equal to the Enthalpy shift. While “enthalpy” is often referred to as “heat content,” most people prefer to refer to it as “enthalpy.”
(d) ENTROPY - Entropy is the amount of thermal energy in a device per unit temperature that can't be used to do useful work. Since work is produced by ordered molecular motion, entropy is also a measure of a system's molecular disorder, or randomness. For several everyday phenomena, the idea of entropy offers profound insight into the direction of spontaneous change.
(e) SATURATED SOLUTION - A saturated solution is a chemical solution that contains the maximum amount of dissolved solute in the solvent. In a saturated solution, the extra solute will not dissolve. A number of factors influence the amount of solute that can be dissolved in a solvent to form a saturated solution.
EDTA is a very common ligand, which like oxalate, binds to many metals. However, unlike oxalate, which forms two bonds, EDTA forms 6 bonds to the metal. A 0.2481g sample of marble was dissolved in 100 mL, and a 10.00 mL aliquot of the solution was titrated to an endpoint with 23.56 mL of 0.01052 M EDTA solution. What is the molecular weight of the marble
Answer:
100 g/mol
Explanation:
The equation of the reaction;
Ca^2+(aq) + EDTA(aq) -----> (CaEDTA)^2-(aq)
Let CA = concentration of EDTA
VA = volume of EDTA
NA= number of moles of EDTA
CB= concentration of marble
VB = volume of marble
NB= number of moles of marble
CAVA/CBVB = NA/NB
CAVANB=CBVBNA
CB = CAVANB/VBNA
CB = 0.01052 * 23.56 * 1/10.00 * 1
CB = 0.02479 M
number of moles = concentration * volume
number of moles = 0.02479 M * 100.00/1000L
number of moles = 2.479 * 10^-3 moles
number of moles = mass/molar mass
molar mass = 0.2481g/2.479 * 10^-3 moles
molar mass = 100 g/mol
Investigation Question: How do organisms get their genes?
THIS ANSWER SHOULD BE 3 OR MORE SENTENCES.
Answer:
from the chromosome..l dont know
Please help with yes or no
explain why people are concerned with the rising level of carbon dioxide in the atmosphere (CO2). What are engineers doing to rebalance the carbon cycle? What can you do to help rebalance the carbon cycle?
Answer:
People are concerned with the rising level of carbon dioxide in the atmosphere because it could be leading to global warming, which is the observed increase of the Earth's temperatures. Engineers are working to rebalance the carbon cycle by designing appliances, buildings and homes that use less energy.
Explanation:
I don’t know if I’m right..........
How is gravity an attractive force?
Help me! Who ever gets to answer and has the best answer gets brainliest (very easy!)
Answer:
Fires --> These consume fuel and convert chemical energy stored in that fuel into thermal light and sound energy.
Decay -->The breakdown of dead plants and animals releases thermal energy.
Earth --> Thermal energy comes from deep inside and it is called geothermal energy.
3. Calculate the number of nickel atoms in a 5-cent coin of mass 0.942g if it was made of an alloy consisting of 75% copper and 25% nickel
Answer:
2.41x10²¹ atoms
Explanation:
mass of nickel that are present in the coin can be determined Using ( 25% nickel) with j mass of coin= 0.942g )
mass of nickel = (0.942g) × (25/100)
= 0.2355g of Nickel
We need to convert this " gram" into " moles"
Mole= mass/ molar mass
Molar mass= 58.69 g/mol
0.2355 g) / (58.69 g/mol)
= 0.004 mol
We need to convert the moles to
number of atoms.
Avogadro's number= 6.023x10²³ atoms/mol
(0.004 × 6.023x10²³ atoms/mol)
=2.41x10²¹ atoms
what charge does nitrogen have
Answer:
3-
Explanation:
Ms. Fremont spent last weekend grading tests . If she spent 4 min on each test , how many hours did it take her to grade all 74 tests ?
Answer:
about 5 hours
Explanation:
When doing this problem you mmust mulitiply 4 x 74 and divide the answer by 60 because 60=1 hour.
The following solutions are prepared by dissolving the requisite amount of solute in water to obtain the desired concentrations. Rank the solutions according to their respective osmotic pressures in decreasing order assuming the complete dissociation of ionic compounds. Rank from highest to lowest osmotic pressure. To rank items as equivalent, overlap them.
A. 1 M MgCl2
B. 1 M KCI
C. 1 M C12
D. H22011
1. Highest osmotic pressure
2. Lowest osmotic pressure
Answer: 1. Highest osmotic pressure : 1 M [tex]MgCl_2[/tex]
2. Lowest osmotic pressure: 1 M [tex]C_{12}H_{22}O_{11}[/tex]
Explanation:
[tex]\pi=i\times C\times R\times T[/tex]
[tex]\pi[/tex]= osmotic pressure
i = Van'T Hoff factor
C = concentration
T = Temperature
1. For 1M [tex]MgCl_2[/tex]
, i= 3 as it is a electrolyte and dissociate to give 3 ions.
[tex]MgCl_2\rightarrow Mg^{2+}+2Cl^{-}[/tex]
2. For 1 M [tex]KCl[/tex]
, i= 2 as it is a electrolyte and dissociate to give 2 ions.
[tex]KCl\rightarrow K^{+}+Cl^{-}[/tex]
3. For 1M [tex]C_{12}H_{22}O_{11}[/tex]
, i= 1 as it is a non electrolyte and do not dissociate.
Thus as vant hoff factor is highest for [tex]MgCl_2[/tex] thus osmotic pressure is highest for 1 M [tex]MgCl_2[/tex]
And as vant hoff factor is lowest for [tex]C_{12}H_{22}O_{11}[/tex] thus osmotic pressure is lowest for 1 M [tex]C_{12}H_{22}O_{11}[/tex]
I need help please. No links/ irrelevant answers or I will report you
Data:
2Fe(s) + O2(g) => 2FeO(s) ΔH = -545.6 kJ
4Fe(s) + 3O2(g) => 2Fe2O3(s) ΔH = -1,643.6 kJ
3Fe(s) + 2O2(g) => Fe3O4(s) ΔH = -1,117.7 kJ
Given the data above, determine the heat of reaction, ΔH, for the reaction:
2 Fe3O4(s) => 2 Fe2O3(s) + 2 FeO(s)
Answer:
ΔH = 46.2 kJ
Explanation:
Hello there!
In this case, according to the given set of reactions and the required one, it is possible to apply the Hess' rule in order to realize the following manipulations to obtain the required reaction:
1. Keep this reaction as it is.
2Fe(s) + O2(g) => 2FeO(s) ΔH = -545.6 kJ
2. Keep this reaction as it is.
4Fe(s) + 3O2(g) => 2Fe2O3(s) ΔH = -1,643.6 kJ
3. Reverse double this reaction so that we obtain:
2Fe3O4(s) => 6Fe(s) + 4O2(g) ΔH = -(-1,117.7 kJ)*2=2235.4kJ
Add them up to obtain:
2Fe(s) + O2(g) + 4Fe(s) + 3O2(g) + 2Fe3O4(s) => 6Fe(s) + 4O2(g) +2Fe2O3(s) + 2FeO(s)
Simplify common terms to obtain:
2 Fe3O4(s) => 2 Fe2O3(s) + 2 FeO(s)
Therefore, the enthalpy of such reaction is:
ΔH = 2235.4kJ -545.6 kJ -1,643.6 kJ
ΔH = 46.2 kJ
Best regards!
Question 5
Complete the following analogy:
Reflection nebulae : blue :: emission nebula:
Greenish-blue
Yellow
Red
Pinkish-red
Answer:
That one is tricky but i would say yellow
Explanation:
Question 2/8
From left to right across the second period of the periodic table,
Answer:
HE
Explanation:
HE is a noble gas
PLEASE HELPPP WILL GIVE 10 PTS AND MARK BRAINIEST TO RIGHT ANSER!!!!!
Roasted coffee beans contain over_____________ chemical compounds
A) 10000000
B) 1000000
C) 1000
D) 10000
Answer:
C. 1000
l think this is correct answer
l hope it's helpful for you
Which sample contains the greatest number of atoms. A sample of Ca that contains 3.40×1024 atoms or a 1.76 mole sample of Be?
The sample of _____ contains the greatest number of atoms.
Answer:
The sample of __Ca___ contains the greatest number of atoms
Explanation:
As we know,
1 mole [tex]= 6.022*10^{23}[/tex] molecular entities (Can be atom, ions or molecules)
Number of atoms in 1.76 mole sample of Be
[tex]= 6.022*10^{23} *1.76\\= 1.059 * 10^{24}[/tex]
The sample of __Ca___ contains the greatest number of atoms
3. Calculate the average atomic mass of sulfur if 95.00% of all sulfur atoms have
a mass of 31.972 amu, 0.76% has a mass of 32.971u and 4.22% have a mass of
33.967u.
Answer:
Average atomic mass = 32.057 u
Explanation:
Average atomic mass = Σ(isotope × abundance)
Average atomic mass = (0.95 × 31.972) + (0.0076 × 32.971) + (0.0422 × 33.967)
Average atomic mass = 32.057 u
Question 1
Describe a procedure you could follow to determine the specific heat of a 45-g piece of metal.
You have 2.2 mol Xe and 2.1 mol F2, but when you carry out the
reaction you end up with only 0.25 mol XeFg. What is the percent
yield of this experiment?
Xe(g) + 2 F2 (g) XeF, (g)
Answer:
Percentage yield = 23.8%
Explanation:
We'll begin by determining the limiting reactant. This can be obtained as follow:
Xe(g) + 2F₂(g) —> XeF₄
From the balanced equation above,
1 mole of Xe reacted with 2 moles of F₂.
Therefore, 2.2 moles of Xe will react with = 2.2 × 2 = 4.4 moles of F₂.
From the above calculation, we can see that a higher amount (i.e 4.4 moles) of F₂ than what was given (i.e 2.1 moles) is needed to react completely with 2.2 moles Xe.
Therefore, F₂ is the limiting reactant and Xe is the excess reactant.
Next, we shall determine the theoretical yield of XeF₄.
This can be obtained by using the limiting reactant as follow:
From the balanced equation above,
2 moles of F₂ reacted to produce 1 mole of XeF₄.
Therefore, 2.1 moles of F₂ will react to produce = (2.1 × 1)/2 = 1.05 moles of XeF₄.
Thus, the theoretical yield of XeF₄ is 1.05 moles.
Finally, we shall determine the percentage yield. This can be obtained as follow:
Actual yield of XeF₄ = 0.25 mole
Theoretical yield of XeF₄ = 1.05 moles
Percentage yield =?
Percentage yield = Actual yield / Theoretical yield × 100
Percentage yield = 0.25 / 1.05 × 100
Percentage yield = 0.238 × 100
Percentage yield = 23.8%
What class of chemicals is responsible for ozone depletion?
What is the pH of a neutral solution at 25ºC?
a. 14
b. 0
c. 1
d. 7
Answer:
d.7 is the correct answer
N₂ + 3H₂ --> 2NH₃
If 207.0 g of H₂ reacts, what mass of NH₃ is produced?
Answer:
69mol
Explanation:
The balanced chemical equation given in this question is as follows;
N₂ + 3H₂ → 2NH₃
The above balanced equation shows that 3 moles of hydrogen gas (H2) reacts to produce 2 moles of ammonia (NH3).
To convert the given mass of hydrogen to moles, we use the following formula:
mole = mass/molar mass
Molar mass of H2 = 2g/mol
mole = 207/2
= 103.5mol
If 3 moles of H2 produce 2 moles of NH3,
Then, 103.5mol of H2 will produce 103.5 × 2 / 3
= 207/3
= 69mol
A gas goes from 1L at 273 K to 2 L when heated. What is the new temp?
Answer:
Given : Diatomic molecule at 273K
'q' absorbed = positive = +100Cal = 100 x 4.184J = 418.4J
'W' done by system = negative = -209J
By first law of thermodynamics;
ΔU = q + W = 418.4 + (-209) = 209.4J
We know for diatomic molecule Cv=25R and CvΔT=ΔU
CvΔT=209.4
25RΔT=209.4
ΔT=5R209.4×2
And, Heat exchange=Cm×ΔT
where; Cm is molar heat capacity
Cm=ΔTHeat Exchange
substituting values for Heat Exchange = 418.4 and ΔT=5R209.4×2
Cm=5R