Answer:
www.doe.virginia.gov/testing/sol/standards_docs/...
Explanation:
did you get the answer??
What is a factual statement about how nature behaves or functions?
a hypothesis
O a law
O a theory
an experiment
Answer:its a law
Explanation:
I passed that quiz 100%, my answer for that question was law
so its law
In reading a line drawing, how do you know where atoms of these elements are in the structure if they are missing from the drawing?
Answer:
The atoms of an element are represented in a chemical line drawing with its chemical formula.
Explanation:
chemical structural drawing helps to represent the pattern for which an element is formed. Chemical elements are made up of atoms that represent their single state.
The line drawing is made up of lines (representing the chemical bond between atoms) and the atoms or various atoms that make up the element.
A buffer contains 0.010 moles of lactic acid (pKa = 3.86) and 0.050 mol of sodium lactate per liter.
(a) Calculate the pH of the buffer.
(b) Calculate the change in pH when 5 mL of 0.5 M HCl is added to 1 L of the buffer.
(c) What pH change would you expect if you added the same quantity (5 mL) of HCl to 1 L of pure water?
Answer:
a. pH = 4.56
b. Change in pH = 0.85
c. Change in pH = 5.4
Explanation:
a. The pKa of lactic buffer is: 3.86.
Using Henderson-Hasselbalch formula for the lactic buffer:
pH = 3.86 + log [Lactate] / [Lactic acid]
Where [] is molarity of each compound but could be taken as moles
Replacing:
pH = 3.86 + log [0.050 moles] / [0.010 moles]
pH = 4.56
b. The HCl added reacts with Lactate producing lactic acid. Moles of HCl are:
5x10⁻³L * (0.5mol /L) = 0.025 moles HCl
Moles of lactate: 0.050moles - 0.025 moles = 0.025 moles
Moles lactic acid: 0.010 moles + 0.025 moles = 0.035 moles
pH = 3.86 + log [0.025 moles] / [0.035 moles]
pH = 3.71
Change in pH = 4.56 - 3.71 = 0.85
c. 1L of pure water has a pH of 7. 0.025 moles of HCl = 0.025 moles H⁺ in 1.005L:
0.025 mol / 1.005L = 0.0249M = [H⁺]
As pH = -log [H⁺]
pH = 1.6
Change in pH = 7.0 - 1.6 = 5.4
Which of the following DOES NOT have 2 significant
figures?
11,000,000,000
0.11
1.001
0.0000011
Answer:
1.001
Explanation:
The Significant Figures are 1 0 0 1, This answer has 4 Significant figures, while the other three have only 2 significant figures
An atom's Lewis dot structure has four dots. Which of the following elements could it be, and why?
Answer: Carbon, because it is in group 14 and has four valence electrons
Explanation: Just did this quiz
Answer:carbon
Explanation:
Which of the following is in intensive property a. mass b. magnetism c shape D. volume
Answer:
b. Magnetism (sorry im very late)
Explanation:
Intensive properties do not depend on size, no matter what it doesn't. For example, magnetism, density, melting and boiling points, and color. All of those support intensive property.
Intensive properties are physical properties that do not depend on the amount or size of the material being measured. In other words, they remain constant regardless of the quantity of the substance.
The correct answer is b. magnetism.
Out of the options provided:
a. mass is an extensive property because it depends on the amount of the substance. If you have more of a substance, you will have a greater mass.
b. magnetism is an intensive property because it remains the same regardless of the size or amount of the material with the magnetic property.
c. shape is not a standard property used to classify intensive or extensive properties. It is more of a description of the object's form.
d. volume is an extensive property because it depends on the size and amount of the substance. If you have more of a substance, you will have a larger volume.
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For the following amino acid, the name, three-letter abbreviation, or one-letter abbreviation is given. Complete the missing information.Name: proline Three letter abbreviation:____________One letter abbreviation:________
Answer:
The correct answer is "Pro; P".
Explanation:
Amino acids are not only identified by its full name, there are three-letter and one-letter abbreviations for each amino acid that helps to annotate sequences and biological processes. In the case of proline, the three letter abbreviation is "Pro" and the one letter abbreviation is "P". Proline got its name for its cyclic structure, that resembles the structure of pyrrole.
Calculate the mass in grams of 8.35 × 1022 molecules of CBr4.
Answer: 45.983 g CBr₄
Explanation:
To convert from moles to grams, you know that we will need molar mass and Avogadro's number.
Avogadro's number: 6.022×10²³ molecules/mol
Molar mass: 331.627 grams/mol
Now that we have what we need, you can use these to solve for grams. [tex]8.35*10^2^2molecules CBr_{4} *\frac{1mol}{6.022*10^2^3molecules} *\frac{331.627 g}{1 mol} =45.983 g[/tex]
Our final answer is 45.983 g CBr₄.
A liquid has a volume of 4mL and a mass of 24 grams. What is the density of the liquid?
Answer:
the density is 6
Explanation:
mass divided by volume equals density
Question 13 of 16
The mass of a piece of metal is 25.4253 grams. When the piece of
metal was dropped into a graduated cylinder that had an initial water
volume of 6.85 cm, the total volume was 9.84 cm? What is the
density of the piece of metal in g/cm??
Answer:
[tex]\rho =8.50g/cm^3[/tex]
Explanation:
Hello,
In this case, due to the volume difference caused by the addition of the metal, one could notice that the volume of the metal is:
[tex]V_{metal}=9.84cm^3-6.85cm^3=2.99cm^3[/tex]
In such a way, given the mathematical definition of density, it turns out:
[tex]\rho =\frac{m}{V}=\frac{25.4253g}{2.99cm^3}\\\\\rho =8.50g/cm^3[/tex]
Regards.
What is the A# of fluoride-19?
Answer:
atomic number of fluorine
is 9
hey can anyone help me with organic chemestry?
Sort the following analytical techniques as either classical methods or instrumental methods.
a) surface analysis
b) precipitation titration
c) gravimetric analysis
d) high performance liquid chromatography
e) potentiometry
f) atmoic spectroscopy
Answer:
Instrumental methods
surface analysis
high performance liquid chromatography
atomic spectroscopy
potentiometry
Classical methods
precipitation titration
gravimetric analysis
Explanation:
Instrumental methods of analysis are those analytical methods in which the responsibility of detection has been removed from human beings and placed on automated instruments while classical methods are those analytical methods in which the responsibility of detection remains the responsibility of human beings.
Many instrumental methods such as HPLC rely on computer screens as readout devices.
Suppose now that you wanted to determine the density of a small crystal to confirm that it is graphite. From the literature, you know that graphite has a density of 2.25 g/cm^3. How would you prepare 20.0 mL of the liquid mixture having that density from pure samples of CHCl3 (d = 1.492 g/mL) and CHBr3 (d = 2.890 g/mL)? (Note: 1 mL = 1 cm^3.)
Answer:
The volume of first and second compound are 9.15 ml and 10.85 ml.
Explanation:
Given that,
Density of graphite = 2.25 g/cm³
Volume of mixture = 20.0 mL
Density of first compound = 1.492 g/ml
Density of second compound = 2.890 g/ml
Let the volume of first mixture = x
The volume of second mixture = (20-x)....(I)
We need to calculate the volume of first compound
Using formula of density of mixture
[tex]\rho=\dfrac{V_{1}\rho_{1}+V_{2}\rho_{2}}{V_{1}+V_{2}}[/tex]
Where, [tex]V_{1}[/tex] = volume of first compound
[tex]V_{2}[/tex] = volume of second compound
[tex]\rho_{1}[/tex] =density of first compound
[tex]\rho_{1}[/tex] = density of first compound
Put the volume into the formula
[tex]2.25=\dfrac{x\times1.492+(20-x)\times2.890}{x+20-x}[/tex]
[tex]45=1.492x+57.8-2.890x[/tex]
[tex]45-57.8=1.492x-2.890x[/tex]
[tex]12.8=1.398x[/tex]
[tex]x=\dfrac{12.8}{1.398}[/tex]
[tex]x=9.15\ ml[/tex]
We need to calculate the volume of second compound
Using equation (I)
[tex]V_{2}=20-x[/tex]
Put the value of x
[tex]V_{2}=20-9.15[/tex]
[tex]V_{2}=10.85\ ml[/tex]
Hence, The volume of first and second compound are 9.15 ml and 10.85 ml.
To prepare 100.0 mL of a 0.0525 M solution of NaCl in water, what mass of sodium chloride is needed? The
molar mass of NaCl is 58.44 g/mol.
Answer:
0.307 g
Explanation:
Step 1: Given data
Volume of solution: 100.0 mL
Molarity of the NaCl solution: 0.0525 M
Molar mass of NaCl: 58.44 g/mol
Step 2: Calculate the moles of NaCl required
The molarity is equal to the moles of solute (NaCl) divided by the liters of solution.
M = moles of NaCl / liters of solution
moles of NaCl = M × liters of solution
moles of NaCl = 0.0525 mol/L × 0.1000 L = 5.25 × 10⁻³ mol
Step 3: Calculate the mass corresponding to 5.25 × 10⁻³ moles of NaCl
5.25 × 10⁻³ mol × 58.44 g/mol = 0.307 g
How does the government control scientific research?
O A. Scientists are dependent upon the government to set ethical
standards.
B. The government can take away money if a scientist is not
following ethical standards.
O C. The government determines which experiments are important.
D. Scientists can do only research that the government supports.
Answer: B) The government can take away money if a scientist is not following ethical standards
Explanation: hope this helped :)
The government control scientific research by taking away money if a scientist is not following ethical standards. Therefore, the correct option is option B.
While it is crucial to recognise that the government's role in scientific research is varied and extends beyond the control of ethical standards, funding agencies and institutions frequently require researchers to follow particular ethical norms and standards when conducting scientific investigations. Failure to adhere to these ethical norms may result in the loss or denial of research funding.
However, it is critical to recognise that the government's role in scientific research extends beyond simply enforcing ethical norms. Governments can also fund and support specific research areas or priorities, create regulations and guidelines for research practises, encourage researcher collaboration, provide infrastructure and resources, and establish policies that shape the overall direction and focus of scientific research.
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Ocean water becomes colder; the density of ocean water increases or decreases?
Answer:
.............increases
At a certain temperature this reaction follows first-order Kinetics with a rate constant of 0.0660
2H1 (g)----------> H2, (g)+I2
Suppose a vessel contains HI at a concentration of 0.310 M. Calculate how long it takes for the concentration of HI to decrease to 0.0558 M. You may assume no other reaction is important. Round your answer to 2 significant digits.
Answer:
After 26.0s, the concentration of HI decreases from 0.310M to 0.0558M.
Explanation:
Based on the reaction of the problem, you have as general kinetic law for a first-order reaction:
ln[HI] = -kt + ln [HI]₀
Where [HI] is actual concentration after time t,
k is rate constant
and [HI]₀ is initial concentration of the reactant.
Initial concentration of HI is 0.310M,
K is 0.0660s⁻¹,
And the actual concentration is 0.0558M:
ln[HI] = -kt + ln [HI]₀
ln[0.0558M] = -0.0660s⁻¹*t + ln [ 0.310M]
-1.7148 = -0.0660s⁻¹*t
26.0s = t
After 26.0s, the concentration of HI decreases from 0.310M to 0.0558M
It takes 330 joules of energy to raise the temperature of 24.6 gbenzene from 21 degrees Celsius to 28.7 degrees Celsius at constantpressure. What is the molar hear capacity of benzene at constantpressure?
Given :
Energy , E = 330 J .
Initial temperature , [tex]T_i=21^oC[/tex] .
Final temperature , [tex]T_f=24.6^oC[/tex] .
Mass of benzene , m = 24.6 g .
To Find :
The molar hear capacity of benzene at constant pressure .
Solution :
Molecular mass of benzene , M = 78 g/mol .
Number of moles of benzene :
[tex]n=\dfrac{24.6}{78} \ mol\\\\n=0.32 \ mol[/tex]
Energy required is given by :
[tex]q=nC_p\Delta T\\\\330=0.32\times C_p\times (28.7-21)\\\\C_p=\dfrac{330}{0.32\times 7.7}\ J\ mol^{-1}^oC^{-1} \\\\C_p=133.9\ J\ mol^{-1}^oC^{-1}[/tex]
Hence , this is the required solution .
Draw structures for compounds that meet the following descriptions in proton NMR:a) C2H6O; one singletb) C3H7Cl; one doublet and one septetc) C4H8Cl2O; two tripletsd) C4H8O2; one singlet, one triplet, and one quartet
Answer:
The structures are shown in the attachments.
Explanation:
Please see the attachments below for the structures.
Explanation:
For the structure in (a)There is only one environment denoted as 'a'.
Using the (n+1) rule to determine the multiplicity, m
where is the number of neighboring Hydrogen, then
Since, n = 0, then
m = 0 + 1 = 1 (which means singlet)
Hence, one singlet
For the structure in (b)There are two environments denoted as 'a' and 'b'
For 'a' ; n = 6
Hence, m = n + 1
m = 6 + 1 = 7 (this means septet)
For 'b'; n = 1
then, m = n + 1
m = 1 + 1 = 2 (this means doublet)
Hence, one septet, one doublet
For the structure in (c)There are two environments denoted as 'a' and 'b'
For 'a' ; n = 2
then, m = n + 1
m = 2 + 1 = 3 (this means triplet)
For 'b' ; n = 2
then, m = n + 1
m = 2 + 1 = 3 (this means triplet)
Hence, two triplets
For the structure in (d)There are three environments denoted as 'a', 'b', and 'c'
For 'a' ; n = 0
Hence, m = n + 1
m = 0 + 1 = 1 (this means singlet)
For 'b' ; n = 3
then, m = n + 1
m = 3 + 1 = 4 (this means quartet)
For 'c' ; n = 2
then, m = n + 1
m = 2 + 1 = 3 (this means triplet)
Hence, one singlet, one triplet, and one quartet
When 1 carbon atom combines with 2 oxygen atoms, the resulting substance is called a
Answer:
Carbon Dioxide
Explanation:
Which is a compound:)
I need these questions answered
Answer:
Three objects with kinetic energy
A ball rolling down the street
Moving Car
Bullet
Law of Conservation of Energy states that the total energy of an isolated system remains constant; it is said to be conserved over time.
Though technically there are limitless forms of both types of energy, officially there's five types of kinetic energy: radiant, thermal, sound, electrical and mechanical and potential energy adds gravitational, nuclear, and elastic.
The stock solution is 100 μM the protocol calls for 10 mL solution of 80, 60, 40 and 20 μM. Compute the table.Target Concentration(μM) Volume of stock(mL) Volume of water(mL)20406080
Answer:
See the answer below
Explanation:
Using the dilution equation:
m1v1 = m2v2
m1 =100 μM, v1 = ?, v2 = 10 mL
In order to prepare 80 μM, then m2 = 80 μM
v1 = [tex]\frac{80*10}{100}[/tex] = 8 mL
In order to prepare 60 μM
v1 = [tex]\frac{60*10}{100}[/tex] = 6 mL
In order to prepare 40 μM
v1 = [tex]\frac{40*10}{100}[/tex] = 4 mL
In order to prepare 20 μM
v1 = [tex]\frac{20*10}{100}[/tex] = 2 mL
Since the final solution has to be up to the 10 mL mark, the complete table would be:
Target Concentration(μM) Volume of stock(mL) Volume of water(mL)
20 2 8
40 4 6
60 6 4
80 8 2
Use the ruler to determine the length of this object. Record your answer to the nearest tenth. The object is ____ long.
Answer: 2.7 cm
Explanation: ~~~~~ there ya go
Describe how matter is classified into mixtures, pure substances, elements, and compounds.
Answer:
Matter can be broken down into two categories: pure substances and mixtures.
Pure substances are further broken down into elements and compounds. ... A chemical substance is composed of one type of atom or molecule.
A mixture is composed of different types of atoms or molecules that are not chemically bonded.
hope this helped
Matter is divided in two categories: pure substances and mixtures.Pure substances are further broken down into elements and compounds.Chemical substance is composed of one type of atom or molecule.A mixture is composed of different types of atoms or molecules .
What is matter?Matter in chemistry, is defined as any kind of substance that has mass and occupies space that means it has volume .Matter is composed up of atoms which may or not be of same type.
Atoms are further made up of sub atomic particles which are the protons ,neutrons and the electrons .The matter can exist in various states such as solids, liquids and gases depending on the conditions of temperature and pressure.
The states of matter are inter convertible into each other by changing the parameters of temperature and pressure.
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What is the maximum length of a polyethene chain with molar mass 10^6 and monomer length 2.5?
Answer:
L=7.0125*10^-5
Explanation:
LET
Length of polyethene chain= L
Molecular weight OF polyethene= MW
Molecular weight of monomer =mw
Monomer length= l
L=(MW/mw) *l
L= (28.05g/mol10^6gmol-1) * 2.5
L=70.125*10^-6
L=7.0125*10^-5
Hence, the length will be L=7.0125*10^-5 .
What sequence should be followed when conducting a laboratory investigation? Make observations, gather experimental data, form a conclusion, state a problem Define a problem, form a hypothesis, gather experimental data, form a conclusion. Form a hypothesis, form a conclusion, gather experimental data, define a problem Gather experimental data, make observations, form a conclusion, for a hypothesis.
Answer:
Define a problem, form a hypothesis, gather experimental data, form a conclusion
Answer:
Make observations, gather experimental data, form a conclusion, state a problem Define a problem, form a hypothesis, gather experimental data, form a conclusion.
Explanation:
Is burning sugar a chemical or physical change? Please provide explanation
Answer:
It is a chemical change
Explanation:
the reason is because the will not be able to materialize back into it's original form.
Photosynthesis by land plants leads to the fixation each year of about 1 kg of carbon on the average for each square meter of an actively growing forest. The atmosphere is approximately 20% O2 and 80% N2, but contains 0.039% CO2 by weight.
A) How much carbon is present in the entire atmosphere lying above each square meter of the earth's surface?
B) At the current rate of utilization, how long would it take to use all the CO2
in the entire atmosphere directly above a forest?
Answer:
a) mass of carbon directly above 1 ( each) square meter of the earth is 1.65kg
b) all CO₂ will definitely be used up from the atmosphere directly above a forest in 1.65 years
Explanation:
first we calculate the moles of carbon
moles = mass/molar mass
= 1kg/12gmol⁻¹
= 1000g/12gmol⁻¹
= 83.33 mol
now using the ideal gas equation
we find the volume of co₂required based on 83.33 moles
PVco₂ = nRT
Vco₂ = nRT/P
Vco₂ = (83.22mol × 0.0821L atm k⁻¹ mol⁻¹ 298 K) / 1 atm
Vco₂ = 2083.73 L
so since CO₂ in air is 0.0390% by volume in the atmosphere, we find the the total amount of air required to obtain 1kg carbon
therefore
Vair × 0.0390/100 = 2038.73L
Vair = (2038.73L × 100) / 0.0390
Vair = 5.23 × 10⁶L
therefore 5.23 × 10⁶ L of air will be required to obtain 1kg carbon
a)
Here we calculate the mass of air over 1 square meter of surface.
Remember that atmospheric pressure is the consequence of the force exerted by all the air above the surface; 1 bar is equivalent to 1.020×10⁴kgm⁻²
NOW
mass of air = 1.020×10⁴kgm⁻² × 1m²
= 1.020×10⁴kg
= 1.020×10⁷g [1kg = 10³g]
we now find the moles of air associated with it
moles = mass/molar mass
= 1.020 × 10⁷g / ( 20%×Mo₂ + 80%×Mn₂)
= 1.020 × 10⁷g / ( 20%×32gmol⁻¹ + 80%×28gmol⁻¹)
= 1.020 × 10⁷g / 28.8 gmol⁻¹
= 354166.67mol
so based on the question, for each mole (air), there is 0.0390% of CO₂
now to calculate the moles of CO₂ we say;
MolesCo₂ = 0.0390/100 × 354166.67mol
= 138.125 moles
Now we calculate mass of CO₂ from the above findings
Moles = mass/molar mass
mass = moles × molar mass
= 138.125 moles × 12gmol⁻¹
= 1657.5g
we covert to KG
= 1657.5g / 1000
mass = 1.65kg
therfore mass of carbon directly above 1 ( each) square meter of the earth is 1.65kg
b)
to find the number years required to use up all the CO₂, WE SAY
Number of years = total carbon per m² of the forest / carbon used up per m² from the forest per year
Number of years = 1.65kgm⁻² / 1kg²year⁻¹
Number of years = 1.65 years
Therefore all CO₂ will definitely be used up from the atmosphere directly above a forest in 1.65 years
What is the density of a silver coin from the following data:
Mass of silver coin 6.581 g
Volume of coin and water 23.7 mL
Volume of water alone 23.1 mL
The answer is assumed to be in g/mL. Please type a numeric value only.
Answer:
you can use math wa, it helps