Answers
Answer:
I think Mary's and Alan's Methods are wrong. Jack is correct.
Explanation:
(M1)(%)+(M2)(%)+(M3)(%)
You will be mulitplying the mass of Isotopes by the percentages, (M1,2,3) are the isotopes. Then you just add the three to get the average.
There isn't any division involved.
Related Questions
What volume of 6.0 M HCl would you need to add to a 800.0 mL of 0.10 M NaAc to give a final pH = 4.30? The pKa of HAc is 4.78. Give the answer in milliliters, using 2 sig. figs.
Answers
Answer:
3.33 ml
Explanation:
We have
pH to be equal to pKa + log [ NaAc / HAc]
pH = 4.30
pKA = 4.78
This is expressed as
4.30 = 4.78 + log [ NaAc / HAc]
log [ NaAc / HAc] = - 0.48
[ NaAc / HAc] = 10^-0.48
= 0.33
Naac/HAc = 0.33
From here we cross multiply to get
NaAc = 0.33 HAc
The ratio can be given as 1 : 0.33 or 3:1
Moles of NaAc = 800 x 0.10 / 1000
= 0.08
With a ratio of 3 : 1 NaAC and HAc
We have 0.06 mol NaAc and 0.02 mol HAc
moles of HCl = 0.02 mol
Volume of Hcl = 0.02x1000 = 20
20/6.0
= 3.33 Ml
The volume of 6.0 M HCL should be 3.33 ml.
Calculation of the volume:Since
pH to be equal to pKa + log [ NaAc / HAc]
pH = 4.30
pKA = 4.78
Now we can do like
4.30 = 4.78 + log [ NaAc / HAc]
log [ NaAc / HAc] = - 0.48
[ NaAc / HAc] = 10^-0.48
= 0.33
Naac/HAc = 0.33
Now
NaAc = 0.33 HAc
The ratio can be given as 1 : 0.33 or 3:1
So,
Moles of NaAc = 800 x 0.10 / 1000
= 0.08
With a ratio of 3 : 1 NaAC and HAc
We have 0.06 mol NaAc and 0.02 mol HAc
And,
moles of HCl = 0.02 mol
So,
Volume of Hcl = 0.02x1000 = 20
= 20/6.0
= 3.33 Ml
hence, The volume of 6.0 M HCL should be 3.33 ml.
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In what ways is a model similar to the thing it represents?
A. A model must be identical to the thing it represents in every way.
B. model can be different from the thing it represents in either its size or the materials it is made of.
C. A model must be identical to the thing it represents in every way except that it can be made out of different materials.
D. A model must be identical to the thing it represents in every way except that it can be a different size.
Answers
Answer: A
Explanation: A model has to be identical to the thing it represents in every way, or people may think something is different than it actually is, because they see it in the model. The answer to the question is A.
What is the shape of the hypothetical molecule XY3
Answers
Answer:
Trigonal planar
Explanation:
If a hypothetical molecule XY3 has three electron domains as shown and no lone pairs, the molecule will be trigonal planar in shape.
From the valence shell electron pair repulsion theory, the shape of molecules is dependent on the number of electron domains in a molecule and weather those electron pairs are lone pairs or bond pairs.
Since lone pairs cause more repulsion and take up more space around the central atom than bond pairs, bond pairs cause the bond angle and molecular geometry to deviate from that predicted on the basis of the valence shell electron pair repulsion theory.
Finally, remember that in a molecule, electron pairs are placed as far apart in space as possible to minimize repulsion.
If a sample contains 78.0 % of the R enantiomer and 22.0 % of the S enantiomer, what is the enantiomeric excess of the mixture?
Answers
Answer: The enantiomeric excess of the mixture =56%
Explanation:
As per given : R isomer = 78%
S isomer = 22%
In chiral substances, Enantiomeric excess is the measure of purity.
So, Enantiomeric excess of the mixture = [tex]|\frac{R-S}{R+S}|\times100[/tex]
[tex]=|\frac{78-22}{78+22}|\times100[/tex]
[tex]=|\frac{56}{100}|\times100\% \\\\=56\%[/tex]
Hence, the enantiomeric excess of the mixture =56%
What is the mass number of an atom with 17 protons, 17 electrons,and 18 nuetrons?
Answers
Answer:
35
Explanation:
the formula is: mass number = protons + neutrons
so 17+18=35
In this periodic table, which color or colors represent the elements that are
metals?
A. Blue and green
B. Orange and green
C. Orange only
D. Blue only
Answers
Answer:
D
Explanation:
the metal are on the left and in the middle
There are various kind of elements that are present in periodic table. Some elements are harmful, some are radioactive, some are noble gases. Therefore, the correct option is option D that is Blue only.
What is periodic table?Periodic table is a table in which we find elements with properties like metals, non metals, metalloids and radioactive element arranges in increasing atomic number.
Periodic table help a scientist to know what are the different types of elements are present in periodic table so that they can discover the new elements that are not being discovered yet.
The elements which is colored blue are elements that are metals. Metals are mostly on the left side of the periodic table. Metals loose lectrons easily. Metals are lustrous, malleable and ductile.
Therefore, the correct option is option D that is Blue only.
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A liquid was known to be either methyl alcohol (CH3OH) or ethyl alcohol (CH3CH2OH). The Dumas method for determining molar masses was used to obtain an approximate molar mass, and this value was used to identify the alcohol. The gaseous alcohol at 98oC and 740Torr has a mass of 0.276g in a Dumas bulb of volume equal to 270mL. Which alcohol was present
Answers
Answer:
Methyl alcohol was present.
Explanation:
To solve this problem we use the PV=nRT formula:
P = 740 Torr ⇒ 740/760 = 0.973 atmV = 270 mL ⇒ 270/1000 = 0.270 LT = 98 °C ⇒ 98 + 273.16 = 371.16 KAnd solve for n:
n = PV/(RT)n = 0.973 atm * 0.27 L / (0.082atm·L·mol⁻¹·K⁻¹ * 371.16 K)n = 8.632 x 10⁻³ molNow we divide the mass and the moles to calculate the molar mass:
0.276 g / 8.632 x 10⁻³ mol = 31.97 g/molMethyl alcohol (CH₃OH) has that molar mass.
A 293.9 mL sample of a 0.275 M solution is left on a hot plate overnight; the following morning the solution is 1.10 M. What volume of solvent in mL has evaporated from the 0.275 M solution
Answers
Answer:
220.4mL were evaporated
Explanation:
First, we are going to calculate the moles of the solution. Then, with the new concentration we can solve the volume of the solution and the evaporated volume:
Moles initial solution:
293.9mL = 0.2939L * (0.275mol / L) = 0.08082 moles of solution.
As the new concentration is 1.10M, the new volume must be:
0.08082 moles of solution * (1L / 1.10mol) = 0.07348L =
73.5mL you have still present in you solution
And evaporated volume is:
293.9mL - 73.5mL =
220.4mL were evaporatedAre homogeneous mixtures only able to be chemically separated into their own individual components?
Answers
Answer:
Are the components of a homogeneous mixture are chemically combined?
Mixtures are physically combined structures that can be separated into their original components. A chemical substance is composed of one type of atom or molecule. ... A homogeneous mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties.
Explanation:
A student completed the lab but found that the total amount of material recovered weighed more than the original sample. What is the error?
Answers
Answer:
Throughout the description section elsewhere here, the interpretation as per the particular circumstance is defined.
Explanation:
Sources of error become basically factors of measurement uncertainty. If the cumulative volume of retrieved material weighed almost as much as the initial sample, and therefore procedural cause of error is still much most probable.Lost compound will be:
= [tex]454-122[/tex]
= [tex]332[/tex]
Percentage of the lost compound will be:
= [tex]\frac{332}{454}\times 100[/tex]
= [tex]73.13 \ percent[/tex]
Volcanologists are scientists who study volcanic eruptions. However, most volcanologists rarely get to witness a volcanic eruptions actually occurring. Instead, many volcanologists use models to study volcanic eruptions. What is the most likely reason why volcanologists often rely on models to study volcanic eruptions?
A.
Volcanic eruptions are too large to be able to see with the naked eye.
B.
Volcanic eruptions are very dangerous events.
C.
Volcanic eruptions are rare occurrences so it is difficult to see them.
D.
Volcanic eruptions take too long to be able to be observed in their entirety.
Answers
Answer:
Volcanic Eruptions are a very dangerous event
Explanation:
Models represent objects, events, and processes in the real world. Models are often used when an object, event, or process occurs too slowly or too quickly; is too small or too large; is too complicated or too dangerous. Volcanic eruptions produce both molten lava and poisonous gases. Therefore, eruptions can be very dangerous. Many volcanologists have lost their lives while observing volcanic eruptions.
What is the speed of a rocket in units of meter/ second if its travels at a speed of 1000 km/minutes?
Answers
Answer:1,080 m
Explanation:
how many moles of oxygen gas can 0.88 mole of hydrogen
Answers
Answer:
0.44 mole of oxygen gas can 0.88 mole of hydrogen peroxide (h2o2) produce, if decomposition is complete.
The image below shows a fault.
a zap
A diagram showing plate movement with labels. The footwall is on the left and the hanging wall is on the right. The plates are moving away from each other.
Which describes the motion of the plates?
The hanging wall and footwall both move vertically.
Shearing is causing the plates to slide past each other.
The hanging wall moves down in relation to the footwall.
Compression is causing the plates to move toward each other.
Answers
Answer:
This is a normal fault. Normal faults usually result from tensile stresses so D is an answer.
Additionally we can see that the hanging wall has moved down relative to the footwall so C is the other answer. =^.^=
Explanation:
this may help you >:3
Answer:
C
Explanation:
What is the molarity of a solution that contains 2.5 g NaCl in 2 L of water?
A. 1.25 M
B. 0.02 M
C. 2.0 M
D. 0.125 M
Answers
Answer:
0.02
Explanation:
I'm not really sure ok so sorry
Which of these terms describes an organism that eats green algae and shrimp?O A. a carnivore
O B. an omnivore
O C. a herbivore
O D. a detrivore
ASAP
Answers
Answer: C. a herbivore
Explanation: it's not a because omnivores eat plants and animals not Detritivores, are heterotrophs that obtain nutrients by consuming detritus
but herbivores eat vegetables and plants
i'm a herbivore i don't eat meat :)
20 points!!! PLEASE AWNSER ASAP!!!
A copper wire was cut into pieces and dropped into a test tube containing acid, Bubbles formed immediately, the liquid in the test tube turned green, and the pieces of wire were no longer visible, which most likely happened to the pieces of copper wire?
А. The copper wire was chemically changed when it was cut and placed in the acid,
B the copper wire was physically changed when it was cut and placed in the acid,
C The copper wire was physically changed when it was cut and chemically changed when it was placed in the acid,
D The copper wire was chemically changed when it was cut and physically changed when it was placed in the acid,
Answers
Answer: i think its A
Explanation:
Answer:
A
Explanation:
Becuase bubbles only come from chemical changes
Which substance is oxidised 2MgO + O2 → 2MgO
Answers
Answer:
Here the oxidizing agent is Mg and the reducing agent is the O2.
This is because Mg is getting taking in O and is reducing itself to form MgO.
This Magnesium oxide, or magnesia, so formed is a white hygroscopic solid mineral that occurs naturally as percales and is a source of magnesium.
Explanation:
A volume of 500.0 mL500.0 mL of 0.140 M0.140 M NaOHNaOH is added to 585 mL585 mL of 0.200 M0.200 M weak acid (Ka=4.71×10−5).(Ka=4.71×10−5). What is the pHpH of the resulting buffer?
Answers
Answer:
pH = 4.50
Explanation:
A weak acid HX reacts with NaOH as follows:
HX + NaOH → H2O + NaX
Initial moles of HX are:
0.585L * (0.200mol / L) = 0.117 moles of HX
The moles of NaOH are moles of NaX that are produced, that means:
0.500L * (0.140mol / L) = 0.07 moles of NaOH = 0.070 moles of NaX produced.
And moles of HX that still in solution are:
0.117 moles - 0.070 moles = 0.047 moles of HX
To find the pH of this buffer (Mixture of a weak acid, HX with its conjugate base, NaX) we use H-H equation:
pH = pKa + log [NaX] / [HX]
Where pKa is -log Ka = 4.327
And [] could be taken as moles of each species.
Replacing:
pH = 4.327 + log [0.070] / [0.047]
pH = 4.50
Which is a product of nuclear fusion?
a nucleus that has a greater mass number than the starting materials
two nuclei that are roughly half the mass of the starting materials
a nucleus that has the same atomic number as the starting materials
two nuclei that have greater atomic numbers than the starting materials
The Answer is: A
Answers
The product of nuclear fusion is a nucleus that has a greater mass number than the starting materials.
What is nuclear fusion?Nuclear fusion occurs when two or more atomic nuclei unite to generate one or more new atomic nuclei and subatomic particles.
The release or absorption of energy is caused by the mass differential between the reactants and products.
If absorption of energy takes place then the formed nuclei will have the higher mass than reactant nuclei.If release of energy takes place then the formed nuclei will have the lighter mass than reactant nuclei.Hence a nucleus that has a greater mass number than the starting materials is the product of the nuclear fusion is .
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Answer:
A
Explanation:
Choose all the answers that apply.
DNA contains coded information for _____.
hibernation
body structure
eye color
height
photosynthesis
Answers
Answer: Hibernation, Eye color and height
Explanation: DNA is the most important molecule of life. Many behaviors are controlled by DNA, such as telling bears how long to hibernate. All of the physical and chemical characteristics of an organism are also controlled by DNA, some cells will form bone, While others will form skin, hair and lungs.
Using the information in the table to the right, calculate the average atomic mass of copper. Report to two decimal places.
Answer: 63.55 amu
Answers
Answer:63.55
Explanation:
is it true that a gas takes up the shape of the container
Answers
Please awnser asap!!! 20 points!!
According to the law of conservation of mass, how many hydrogen and chlorine atoms are required for this reaction?
A 1 hydrogen atom and 1 chlorine atom
B 1 hydrogen atom and 2 chlorine atoms
C 2 hydrogen atoms and 1 chlorine atom
D 2 hydrogen atoms and 2 chlorine atoms
Answers
EXPLANATION: if you separate each equation the final product will end up with 2 hydrogen and 2 chlorine atom
Answer: d
Explanation:
Did this last year
What is the order of a reaction with a half-life that is directly proportional to initial concentration? Select the correct answer below: Zero order First order Second order None of the above
Answers
Answer:
Zero order
Explanation:
A zero order reaction is one in which the rate of reaction is independent of the concentration of reactants.
In a zero-order reaction, the half-life of the reactants is directly proportional to the initial concentration of the reactants . As initial concentration increases, the half-life for the reaction increases likewise and vice versa.
ITS DUE IN 12 MINUTES PLEASE HELP ME :((
Answers
Calculate the pH at of a solution of trimethylammonium chloride . Note that trimethylamine is a weak base with a of . Round your answer to decimal place.
Answers
Answer:
pH = 11.9
Explanation:
The solution is 0.93M. The pKb is 4.19
The general equation of a weak base, X, is:
Kb = [OH⁻] [XH⁺] / [X]
Where Kb is 10^-pKb = 6.457x10⁻⁵
[OH⁻] and [XH⁺] comes both from the same equilibrium and its concentration, X, is the same = [OH⁻] = [XH⁺] = X
And [X] could be taken as the initial concentration of the weak acid, 0.93M
Kb = [OH⁻] [XH⁺] / [X]
6.457x10⁻⁵ = X² / 0.93M
6x10⁻⁵ = X²
X = 7.749x10⁻³M = [OH⁻]
As pOH = -log[OH⁻]
pOH = 2.11
pH = 14 - pOH
pH = 11.9The image shows four organelles: which of these controls what enters and exits the cell?
Answers
Answer:
The cell membrane.
Explanation:
stion 1/2 Which of the following is a physical property?
A. The boiling point o a certain alcohol is 78 degrees Celsius
B. Diamond is very hard
C. Sugar ferments to form alcohol
D. A metal wire conducts an electric current
Answers
HELP ASAP You have a mixture of water, alcohol, and iron. Tell me, how would you separate them from each other?
Answers
Answer:
Put them on boiling wtaer, and they will sart to seperate
Explanation: