Solution :
Partition coefficient Kd
[tex]$=\frac{\frac{\text{mass of caffeine in } CH_2Cl_2}{\text{volume of } CH_2Cl_2}}{\frac{\text{mass of caffeine in water}}{\text{volume of water}}}$[/tex]
= 9.0
A). 1 x 200 mL extraction :
Let m be the mass of caffeine in the water
Mass of caffeine in [tex]$CH_2Cl_2$[/tex] = 100 - m
[tex]$\frac{\frac{100-m}{200}}{\frac{m}{200}} = 9.0$[/tex]
[tex]$=\frac{100-m}{m} = 9.0$[/tex]
[tex]$= 10 m = 100$[/tex]
m = 10
Mass remaining in coffee = m = 10 mg
B). 2 x 100 mL extraction :
First extraction :
Let [tex]$m_1$[/tex] be the mass of caffeine in the water
Mass of caffeine in [tex]$CH_2Cl_2$[/tex] = [tex]$100-m_1$[/tex]
[tex]$\frac{\frac{100-m_1}{100}}{\frac{m_1}{200}} = 9.0$[/tex]
[tex]$=\frac{100-m_1}{m_1} = 4.5$[/tex]
[tex]$ 5.5 \ m_1 = 100$[/tex]
[tex]$m_1$[/tex] = 18.18
Mass remaining in coffee = [tex]$m_1$[/tex] = 18.18 mg
Second Extraction :
Let [tex]$m_2$[/tex] be the mass of caffeine in the water
Mass of caffeine in [tex]$CH_2Cl_2$[/tex] = [tex]$18.18-m_2$[/tex]
[tex]$\frac{\frac{18.18-m_2}{100}}{\frac{m_2}{200}} = 9.0$[/tex]
[tex]$=\frac{18.18-m_2}{m_2} = 4.5$[/tex]
[tex]$ 5.5 \ m_2 = 18.18$[/tex]
[tex]$m_2$[/tex] = 3.3
Mass remaining in coffee = [tex]$m_2$[/tex] = 3.3 mg
A certain protein transports a sodium ion from the inside of the cell membrane to the outside using active transport. Which of the following must be true? A. There is no change in concentration before or after transport. B. The transport process did not use chemical energy. C. After transport, the concentration of protein in the cell decreases. D. After transport, the concentration of sodium is lower inside the cell.
The percent composition by mass of nitrogen in NH OH (gram-formula mass = 35 grams/mole) is equal to
Answer:
the percentage composition of mass of nitrogen in NH OH is 42.86 %
What is 6.25 in scientific notation?
Which statement best describes how matter and energy is cycled through the ecosystem?
A. Energy is recycled in an ecosystem, but matter is not recycled.
B. Matter and energy are both cycled throughout an ecosystem, and much of the energy at each level is changed to heat energy.
C. Energy is gained in each level on the energy pyramid, and matter is lost in an ecosystem.
D. Matter and energy are the same.
D. Matter and energy are the same.
Please answer this question
Answer:
K^2O
Explanation:
I remember a question like this one and I got it right its K^2O
(aka its C)
What is the molar mass of PbSO4?
Answer:
=303.2g
Explanation:
molar mass of Pb = 207.2g
atomic mass of S = 32g
atomic mass of O = 16g
Solution
PbSO4
= 207.2 + 32 + 4 (16)
= 239.2 + 64
= 303.2 g
The molar mass of compound lead sulfate is 207.2 g.
Molar mass of a compound or a molecule is defined as the mass of the elements which are present in it.The molar mass is considered to be a bulk quantity not a molecular quantity. It is often an average of the of the masses at many instances.
Molar masses of an element are given as relative atomic masses while that of compounds is the sum of relative atomic masses which are present in the compound.
atomic mass of S = 32g
atomic mass of O = 16g
PbSO₄= 207.2 + 32 + 4 (16)= 239.2 + 64 = 303.2 g.
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I need help with this chem problem!
please help me
is for my daughter
Answer:
I think you have to freeze the water itself then take the temp with a thermometer ️of each one then record how long it takes each one to start freezing then how long it takes for it to melt
Explanation:
sorry if I'm wrong but you have to do the experiment yourself then fill it out
A group of students is setting up a test to see whether earthworms, like those shown in the photo, prefer rough or smooth surfaces
Answer:
they like smooth
Explanation:
Which system is affected by the process of weathering?
the hydrosphere
the atmosphere
the biosphere
the geosphere
[tex] \huge \colorbox{pink}{Answer☟︎︎︎}[/tex]
When ice melts, liquid water performs the act of erosion by carrying away the tiny rock fragments lost in the split. This specific process (the freeze-thaw cycle) is called frost weathering or cryofracturing. Temperature changes can also contribute to mechanical weathering in a process called thermal stress.
At room temperature, oxygen is a gas and hydrogen is a gas. When they combine at room temperature, they form a _______________.
Answer: they can combine to form water or hydrogen peroxide.
Explanation:
sorry if it wrong i just looked it up lol. hope this helps tho
what makes a substance a good insulator
Answer:
zoo wee mama
Explanation:
The particles that make up an object are held together by bonds. Insulators have strong bonds that hold their particles rigidly in place. This prevents particles from gaining energy and increasing the temperature. Wool, dry air, plastics, and polystyrene foam are all examples of good insulators.
Copper has a specific heat of 0,900 J(g C). How much energy in kJ is needed to raise the temperature of a 700 g block of aluminum from 30.7°C to 82,1C?(show your steps)
Answer:
32.4 kJ
Explanation:
Given that:
Specific heat capacity fo copper, c = 0.9
Mass of copper, m = 700 g
Temperature change, dθ ;t2 - t1 = (82.1 - 30.7) = 51.4
Energy required, E = mcdθ
E = 700 * 0.9 * 51.4
E = 32382 J
Energy required on kJ
32382 / 1000
= 32.382 kJ
= 32.4 kJ
CAN SOMEONE PLEASE HELP ME I WILL MARK AS BRAINLIEST :(
Answer:
ok so i did the problem and the answer was 8e+29
Explanation:
i dont really know what the answer is but thats the answer i got
sorry if this didnt help
NEEED HELP NOW
A new drug has been released to the public and is popular among
consumers. It is effective in relieving high blood pressure. However, it has
altered some patients' personalities. Which stage of the engineering process
may address this negative side effect?
A. Evaluating test results
B. Looking for improvements
C. Screening
D. Testing
Answer: looking for improvements
Explanation:
Answer:
B. Looking for improvements
Explanation:
took the quiz and got in right on a pex
which property is a property of water
Answer: Polarity, Boiling and Freezing Points, Specific Heat Capacity, Density, Surface Tension, Heat of Vaporization and Vapor Pressure, Capillary Action, Solid State (Ice), Liquid State (Liquid Water), Gas State (Steam),
Explanation: Water molecules are polar, so they form hydrogen bonds. This gives water unique properties, such as a relatively high boiling point, high specific heat, cohesion, adhesion, and density.
number of molecules in lithium oxide
4li2O
Answer:
Explanation:
Lithium is in group 1 so there's 1 outermost shell electron.
Oxygen is in group 6 so there's 6 outermost shell electron.
To react lithium with oxygen, we need 2 lithium and 1 oxygen
Each lithium transfer 1 electron to the oxygen and oxygen gain 2 electrons.
[tex]Li_{2}O\\[/tex] formed.
If there's 4 lithium oxide, 4 molecules will be there.
If you mean how many ATOMS are there, there will be 3×4=12 atoms.
molar mass of Mg(CO3)
Answer:
[tex]\boxed {\boxed {\sf 84.313 \ g/mol}}[/tex]
Explanation:
The molar mass is the mass per mole of an element or substance. The values for atomic mass on the Periodic Table are used as the molar mass. Look up the molar masses for the elements in the formula.
Mg: 24.305 g/molC: 12.011 g/molO: 15.999 g/molAnalyze the formula. Magnesium and carbon have no subscript, so there is only one atom of each. Oxygen has a subscript of 3, so there are 3 atoms and the mass has to be multiplied by 3.
MgCO₃= 24.305 + 12.011+ 3(15.999) MgCO₃= 24.305+12.011+47.997=84.313 g/molThe molar mass of magnesium carbonate is 84.313 grams per mole.
Is the number of total molecules on the left side of a balanced equation always equal to the number of total molecules on the right side of the equation
Answer:
No
Explanation:
No, but the total mass of reactants must equal the total mass of products to be a balanced equation.
Example: Consider the following reaction ...
3H₂ + N₂ => 2NH₃ and 'amu' is atomic mass units (formula weights from periodic table)
In terms of molecules, there are 4 molecules on the left (3 molecular hydrogens (H₂) and 1 molecular nitrogen (N₂) and 2 molecules of ammonia on the right side of equation arrow. ∑reactant molecules ≠ ∑product molecules.
In terms of mass of reactants & mass of products, the 3H₂ + N₂ => 6amu + 28amu = 34amu & mass of products (2NH₃) => 2(14amu) + 6(1amu) = 34amu for sum of product masses.
∑mass reactants = ∑mass products <=> 34amu = 34amu.
The expression '∑mass reactants = ∑mass products' as applied to chemical equations is generally known as 'The Law of Mass Balance'.
which graph shows the volume amount of gas relationship expected for an ideal gas, known as Avogadro's law
Answer:
The answer is A
Explanation:
I got it right on the test
What is produced when concentrated aqueous sodium chloride is electrolysed?
The burning of fossil fuels, like coal, oil, and natural gas, DO NOT contribute to the presence of greenhouse gases in the atmosphere.
True
or
False
Answer:
false statements because they are all nonrenewable resources
"A bicycle's brakes apply 299 N of frictional force to the wheels as the bike moves 24 m
for 3.0 s. How much WORK do the brakes do?"
Answer:
0.62 N
Explanation:
first of all: 3.0 s = 0.05 m
Let ? be the work that brakes do at 3.0s
24 m ----> 299 N
0.05 m ---->?
? = (0.05 m x 299 N)/ 24
? = (14.95)/ 24
? = 0.622 N
helppppppppppppppppp
Answer:
b
Explanation:
What BEST describes the relation of a new population to an increase in the amount of space it occupies? a - The population will die out
b - The population will remain constant
c - The population will grow exponentially
How are fossil fuels formed from geologic processes?
Answer:
Explanation:
Fossil fuels are hydrocarbons, namely, petroleum , coal and natural gas, formed from buried combustible geologic deposits of organic and natural materials. They are created from decayed animals and plants that convert into coal, crude oil or heavy oil due to constant exposure to pressure and heart in the earth’s crust.
The compounds that make up plankton and plants convert into fossil fuels. Plankton decomposes into natural gas and oil, while plants become coal. Nowadays, humans extract these resources through coal mining and the drilling of oil.
What are fossil fuel ?The term fossil fuel is defined as they are made from decomposing plants and animals. An example of a fossil fuel is coal, as well as oil and natural gas.
Because they were generated from the petrified, buried remains of plants and animals that once lived millions of years ago, coal, crude oil, and natural gas are all referred to as fossil fuels.
Thus, The remains of these animals underwent a transformation into what we now know as fossil fuels over millions of years at great pressure and high temperature.
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An example of a suspension is:
A. blood
B. gelatin
C. muddy water
D. milk
PLEASE PLEASE I do not understand may someone kindly help me pls
Answer:
It can be verified since the information came from a government article. Or you could trust the magzine/general article if its from a well known article. Explanation:
you get the point, you can add on to this. I can't make it the best since im not in your class learning. Good luck
HELP I WILL GIVE YOU BRAINLIST!!!
Pick one substance (ex: water and table salt) and compare two of the atoms connected to each other (ex: H and O, Na and Cl) and answer the following questions for each pair:
1)Are they close or far away from each other on the periodic table?
Do they have similar atomic radii?
2)Do they have a large or small difference in ionization energy? What about for electron affinity?
1) How many molecules are in 0.02 moles of beryllium iodide?
Answer:
3 grams??
Explanation:
I think this would be the answer you are looking for.