Answer:
The concentration of chloride ion is [tex]2.82\times10^{-3}\;mol/L[/tex]
Explanation:
We know that 1 ppm is equal to 1 mg/L.
So, the [tex]Cl^-[/tex] content 100 ppm suggests the presence of 100 mg of [tex]Cl^-[/tex] in 1 L of solution.
The molar mass of [tex]Cl^-[/tex] is equal to the molar mass of Cl atom as the mass of the excess electron in [tex]Cl^-[/tex] is negligible as compared to the mass of Cl atom.
So, the molar mass of [tex]Cl^-[/tex] is 35.453 g/mol.
Number of moles = (Mass)/(Molar mass)
Hence, the number of moles (N) of [tex]Cl^-[/tex] present in 100 mg (0.100 g) of [tex]Cl^-[/tex] is calculated as shown below:
[tex]N=\frac{0.100\;g}{35.453\;g/mol}=2.82\times 10^{-3}\;mol[/tex]
So, there is [tex]2.82\times10^{-3}\;mol[/tex] of [tex]Cl^-[/tex] present in 1 L of solution.
Calculate the pH of a solution containing a caffeine concentration of 455 mg/L . Express your answer to one decimal place.
Answer:
Explanation:
Caffeine is a weak base with pKb = 10.4
Kb = 10⁻¹⁰°⁴ = 3.98 x 10⁻¹¹
molecular weight of caffeine = 194.2
455 x 10⁻³ g / L = 455 x 10⁻³ / 194.2 moles / L
concentration of given solution a = 2.343 x 10⁻³ M
Let the caffeine be represented by B .
B + H₂O = BH + OH⁻
a - x x x
x² / ( a - x ) = Kb
x² / ( a - x ) = 3.98 x 10⁻¹¹
x is far less than a so a -x is almost equal to a
x² = 3.98 x 10⁻¹¹ x 2.343 x 10⁻³ = 9.32 x 10⁻¹⁴
x = 3.05 x 10⁻⁷
[ OH⁻ ] = 3.05 x 10⁻⁷
pOH = - log ( 3.05 x 10⁻⁷ )
= 7 - log 3.05
= 7 - 0.484 = 6.5
pH = 14 - 6.5 = 7.5
The pH of 455 mg/L of caffeine is 7.5
Using the formula;
Mass concentration = molar concentration × molar mass
Molar mass of caffeine = 194 g/mol
Mass concentration of caffeine = 455 mg/L
Molar concentration = Mass concentration/molar mass
Molar concentration = 455 × 10^-3g/L/194 g/mol
= 0.00235 M
Let Caffeine by depicted by the general formula BH
We can now set up the ICE table as follows;
:B + H2O ⇄ BH + OH^-
I 0.00235 0 0
C - x +x +x
E 0.00235 - x x x
Note that water is present in large excess
Again; pKb of caffeine =10.4
Kb = Antilog[-pKb]
Kb = Antilog [-10.4]
Kb = 3.98 × 10^-11
Kb = [BH] [OH^-]/[:B]
3.98 × 10^-11 = [x] [x]/[ 0.00235 - x ]
3.98 × 10^-11 [ 0.00235 - x ] = [x] [x]
9.4 × 10^-14 - 3.98 × 10^-11x = x^2
x^2 + 3.98 × 10^-11x - 9.4 × 10^-14 = 0
x = 3.1 × 10^-7 M
Recall [BH] = [OH^-] = 3.1 × 10^-7 M
Now;
pOH = - log [OH^-]
pOH = log [3.1 × 10^-7 M]
pOH = 6.5
But;
pH + pOH = 14
pH = 14 - pOH
pH = 14 - 6.5
pH = 7.5
The pH of 455 mg/L of caffeine is 7.5
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Missing parts
Caffeine (C8H10N4O2) is a weak base with a pKb of 10.4. Calculate the pH of a solution containing a caffeine concentration of 455 mg/L.
Which of these is the best definition of biotechnology??
A) The study of chemical processes in living things
B) the use and application of living things and science
C) the application of engineering principles to solve medical problems
D) the study of forces
Stephen learned that there are two forces that keep the moon in orbit around Earth. How do these forces keep the moon from flying off into space?
A. Gravity keeps the moon in motion, and inertia attracts the moon toward Earth.
B. Gravity attracts the moon toward Earth, and inertia keeps the moon in motion.
C. Gravity attracts the moon toward Earth, and the distance keeps it from going further away.
D. Mass weighs the moon down so it stays close to Earth, and inertia keeps the moon in motion.
Answer:
b
Explanation:
Answer:
Gravity attracts the moon Earth, and Inertia keeps the moon in motion.
Explanation:
Please tell me the answers to A, B, and C
Answer:
A=element
B=compond
C=solution
help me please loves
Answer:
K and ba
Explanation:
Answer: K and Ba
Explanation:
1. Marisa determined the melting point of a substance to be 24.5C. Find the percent error of her measurement if the actual melting point is 31.2C.
Answer:
[tex]\%\ Error = 21.5\%[/tex]
Explanation:
Given
[tex]Measured = 24.5[/tex]
[tex]Actual = 31.2[/tex]
Required
Determine the percentage error
First, we need to determine the difference in the measurement
[tex]Difference = |Actual - Measured|[/tex]
[tex]Difference = |31.2 - 24.5|[/tex]
[tex]Difference = |6.7|[/tex]
[tex]Difference = 6.7[/tex]
The percentage error is calculated as thus:
[tex]\%\ Error = \frac{Difference * 100\%}{Actual}[/tex]
[tex]\%\ Error = \frac{6.7 * 100\%}{31.2}[/tex]
[tex]\%\ Error = \frac{670\%}{31.2}[/tex]
[tex]\%\ Error = 21.4743589744\%[/tex]
[tex]\%\ Error = 21.5\%[/tex] approximated
2.
(3x – 4y = -10
(6x + 3y = –42
SOLUTION:
Answer:
Is like for solving for the solution for both equations??
Pls help, and fast plsssssssss
Answer:
The cell on the left is animal, The cell on the right is a plant cell.
Explanation:
1: cell membrane
2: chloroplast
3: cell wall
4: vacuole
5: mitochondria
6:nucleus
7: lysosome
8: cytoplasm
Things to remember, only plant cells have cell walls. Plant cells are the only ones that have chloroplast.
Which of these is the term for the rate of flow of energy in a circuit?
velocity
electricity
resistance
current
4.5 tons → lbs
4.5 tons equals how many pounds
Answer:
9000 pounds
Explanation:
9000 pounds
Answer: 9000 lbs.
Explanation: 4.5 tons = 9000 pounds.
Please help me ! Thank you
Answer:
10
Explanation:
What types of materials are better at absorbing energy from radiation?
Answer:
Explanation:
Materials are clothes and heavy rope
calculate the mass of N2 gas which has a volume 0.227 at STP
what is functional group of ethers?
Answer:
Explanation:The ether functional group consists of an oxygen atom that forms single bonds with two carbon atoms
can someone pweaseee help me on this ??
Answer:
Be
Explanation:
The atomic radius decreases as you go from left to right in a period. Be has the largest radius out of those given elements.
All living things are made of one or more cells. Which is true of all cells?
Name the following ionic compound: Ba(OH)2*2H2O
Metals typically lose electrons to complete their octet in a reaction with non-metals, whereas non-metals typically acquire electrons to complete their octet. Ionic compounds are typically formed via reactions between metals and nonmetals. The given compound barium hydroxide is ionic.
Ions with the opposite charge are carefully packed together to form crystalline solids. Ionic compounds typically result from reactions between metals and non-metals. The electrostatic interaction between the positive and negative ions holds ionic solids together.
Baryta, commonly known as barium hydroxide, has the chemical formula Ba(OH)₂. It is an odorless, clear-white powder. It has a toxic disposition. It is ionic in nature, with two hydroxide ions per molecule of barium hydroxide (Ba(OH)₂ in an aqueous solution an example.
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Which of the following is an Elementary compound?
A. CO2
B. N2
C. SO2
D. H2S
heeeeeeeeeelp please please please
Answer:
Explanation:
In my opinion the answer should be SO2
Answer:
a should be answer i think.
If your hypothesis is incorrect you should...
When does carbon dioxide absorb the most heat energy?
during freezing
during deposition
during sublimation
during condensation
Answer:
during sublimation
Explanation:
just took the test
Pb12 (s) = Pb+2 (aq)
+
2 ]- (aq)
Answer:
this
Explanation:
What is the unit rate of the better deal? (Number answers only.)
LaTeX: \frac{160\:miles}{5\:gallons}\:or\:\frac{315\:miles}{9\:gallons}160 m i l e s 5 g a l l o n s o r 315 m i l e s 9 g a l l o n s
The better deal has a unit rate of [m] miles per gallon.
Question 11
4 pts
Using the formula 2H202 --> 2H2O + O2, if 7.30 moles of peroxide are
decomposed, how many moles of oxygen will be formed?
Answer:
3.65 mol O₂
Explanation:
Step 1: RxN
2H₂O₂ → 2H₂O + O₂
Step 2: Define
Given - 7.30 mol H₂O₂
Solve - x mol O₂
Step 3: Stoichiometry
[tex]7.30 \hspace{3} mol \hspace{3} H_2O_2(\frac{1 \hspace{3} mol \hspace{3} O_2}{2 \hspace{3} mol \hspace{3} H_2O_2} )[/tex] = 3.65 mol O₂
What is the Kc equilibrium-constant expression for the following equilibrium? S8(s) + 24F2(g) 8SF6(g)
Answer:
[tex]Kc=\frac{[SF_6]^8}{[F_2]^2^4}[/tex]
Explanation:
Hello.
In this case, for the undergoing chemical reaction:
[tex]S_8(s) + 24F_2(g) \rightleftharpoons 8SF_6(g)[/tex]
We consider the law of mass action in order to write the equilibrium expression yet we do not include S8 as it is solid and make sure we power each gaseous species to its corresponding stoichiometric coeffient (24 for F2 and 8 for SF6), thus we obtain:
[tex]Kc=\frac{[SF_6]^8}{[F_2]^2^4}[/tex]
Best regards!
Helpppp!!!!! Please help me
Answer:
10.)Weight and mass are different because only weight describes the force of gravity on an object.
11.)On a planet with more mass than earth your weight would be higher because greater gravitational pull.
On a planet with less mass than earth your weight would be less because of the lower gravitational pull.
Explanation:
Is air a homogeneous heterogeneous mixture or substance
Answer:
look at the explanation
Explanation:
The air that you breathe is a homogeneous mixture of oxygen, nitrogen, argon, and carbon dioxide, along with other elements in smaller amounts. Because each layer of the Earth's atmosphere has a different density, each layer of air is its own homogeneous mixture.
Hope this helps. :)
A chemist decomposes samples of several compounds; the masses of their constituent elements are listed. Calculate the empirical formula for each compound.
a. 1.245 g Ni, 5.381 g I,
b. 2.677 g Ba, 3.115 g Br,
c. 2.128 g Be, 7.557 g S, 15.107 g
Answer:
you can see the empirical formula at the pic
The empirical formula for compound (a) is NiI2, (b) is BaBr2 and (c) is BeS.
What is empirical formula?
Empirical formula of a compound is defined as the simplest whole number ratio of atoms present in a compound.
(a) 1.245 g Ni : 5.381 g I
Mole of Ni ; Mole of I = 1.245/59 : 5.381/127 = 0.02 : 0.04 = 1:2
So the formula is NiI2
(b) 2.677 g Ba : 3.115 g Br
Mole of Ba : Mole of Br = 2.677/137 : 3.115/60 = 0.019 : 0.038
= 0.02 : 0.04 = 1:2
So the formula is BaBr2
(c) 2.128 g Be : 7.557 g S
Mole of Be : Mole of S = 2.128/9 : 7.557/32 = 0.2 : 0.2 = 1:1
So the formula is BeS
Thus, empirical formula for compound (a) is NiI2, (b) is BaBr2 and (c) is BeS.
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1. Which statement describes a compound?
A. It contains a solute.
B. Its composition can vary.
C. Its combination of atoms never changes.
D. Its components keep separate properties.
2. Which item is NOT a type of matter?
A. force
B. mixture
C. element
D. compound
3. Which combination can be used to classify all the matter on Earth?
A. forces and energy
B. atoms and elements
C. solvents and solutes
D. substances and mixtures
An ion formed from an atom has a 1- charge. The number of electrons present in the ion is 36 and the number of neutrons is 46. Identify the element by typing the name. For example: Hydrogen or Sodium.
Answer:
Bromine can become an ion when it gains an electron. Br- is a negative ion. Its known as an anion. Bromine has 35 protons=35 electrons. one added electron gives it 36 electrons and it becomes an anion.
Explanation:
Bromine can have isotopes having 44 and 46 neutrons.
as a student,living in the philippines considered to be part of the global south,how are you going to compete and survive challenges of globalization?
Answer:
Natural Selection
Explanation:
match the number of negative charges to the number of positive charges to make each combination balanced (see image for answer) just say like thanks, or a fun fact or something for ten points in the answers lol
Answer : The correct match is:
1 positive charge = 1 negative charge
2 positive charges = 2 negative charges
3 positive charges = 3 negative charges
Explanation :
As we now that there are three subatomic particles which are protons, electrons and neutrons.
The protons and neutrons are located inside the nucleus and electrons are located around the nucleus.
The protons are positively charged, the electrons are negatively charged and neutrons are neutral.
As we know that all the things are made up of charges and opposite charges attract to each other.
In a neutral atom, the positive charges and negative charges are balanced in an object. That means, in neutral atom the number of positive charges are equal to the negative charges.
So we can say that:
1 positive charge = 1 negative charge
2 positive charges = 2 negative charges
3 positive charges = 3 negative charges
Answer:
1 positive---- 1 negative
2 positive---- 2 negative
3 positive---- 3 negative
Explanation:
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