Answer:
o232
Explanation:
Caffeine (C8H10N4O2) is a weak base with a pKb of 10.4. Calculate the pH of a solution containing a caffeine concentration of 415 mg/L .
Answer:
pH → 7.47
Explanation:
Caffeine is a sort of amine, which is a weak base. Then, this pH should be higher than 7.
Caffeine + H₂O ⇄ Caffeine⁺ + OH⁻ Kb
1 mol of caffeine in water can give hydroxides and protonated caffeine.
We convert the concentration from mg/L to M
415 mg = 0.415 g
0.415 g / 194.19 g/mol = 2.14×10⁻³ mol
[Caffeine] = 2.14×10⁻³ M
Let's calculate pH. As we don't have Kb, we can obtain it from pKb.
- log Kb = pKb → 10^-pKb = Kb
10⁻¹⁰'⁴ = 3.98×10⁻¹¹
We go to equilibrium:
Caffeine + H₂O ⇄ Caffeine⁺ + OH⁻ Kb
Initially we have 2.14×10⁻³ moles of caffeine, so, after the equilibrium we may have (2.14×10⁻³ - x)
X will be the amount of protonated caffeine and OH⁻
Caffeine + H₂O ⇄ Caffeine⁺ + OH⁻ Kb
(2.14×10⁻³ - x) x x
We make the expression for Kb:
3.98×10⁻¹¹ = x² / (2.14×10⁻³ - x)
We can missed the -x in denominator, because Kb it's a very small value.
So: 3.98×10⁻¹¹ = x² / 2.14×10⁻³
√(3.98×10⁻¹¹ . 2.14×10⁻³) = x → 2.92×10⁻⁷
That's the [OH⁻]. - log [OH⁻] = pOH
- log 2.92×10⁻⁷ = 6.53 → pOH
14 - pOH = pH → 14 - 6.53 = 7.47
A hot air balloon rises because the fire warms up the air and the air circulates to fill the balloon and lift it at the same time. What type of heat transfer is this?
Answer:
convection
Explanation:
Convection is a mode of heat transfer in which the particles of a substance actually move from place to place.
During convection, warmer and less dense air rises while colder and denser air sinks downwards under gravity.
Hence; when hot air balloon rises because the fire warms up the air and the air circulates to fill the balloon and lift it at the same time, convection has taken place.
Name the following aldehyde:
CH3CH2CH2CH2CH2CHO
A) Hexanol
B) Pentahal
C)Hexanal
D)Hepthal
NO SCAM ANSWERS
Answer:
C, hexanal
Explanation:
Option C is correct. The given name of the aldehyde CH3CH2CH2CH2CH2CHO is Hexanal
Aldehydes are organic compounds formed from the oxidation of alcohols. The contains the group -CHO
Given the compound CH3CH2CH2CH2CH2CHO
For us to name this compound, we need to first know:
The longest chain in the compoundSince there are 6 carbons in the chain, hence the alkane equivalent will be hexane.
Since it is an aldehyde compound.
General naming = alkane name + group name of aldehyde
compound name = alkane name + (-nal)
compound name = hexanal
Hence the name of the given aldehyde is Hexanal
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Match each scientist to their discovery regarding the atom
Thomson
Electrons have a charge of -1.
Rutherford
Atoms are indivisible
Millikan
Atoms have a positive nucleus
Dalton
Atoms contain electrons.
Answer:
Thomson--atoms cotain electron
Ernest Rutherford--atoms have a positive nucleus
R.A Millikan--electrons have Q=-1
Dalton--atoms are indivisible
Millikan---> Electrons have a charge of -1
Rutherford ---> Atoms have a positive nucleus
Thomson -----> Atoms contain electrons
Dalton --------> Atoms are indivisible
The atomic theory went through several modifications and different scientists proposed various models of the atom until our present conception of the atom was developed.
The atom was first defined as the smallest indivisible particle of a substance. This idea of "indivisibility" of the atom stems from Dalton's theory.
The fact that atoms were composed of negatively charged electrons was proven by the experiments of J.J Thompson using the cathode ray tube. Millikan's charge to mass experiment showed that the electron has a charge of -1.
Rutherford, in his famous gold foil experiment showed that atoms were composed of a positively charged nucleus.
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At STP (101.3 kPa, 0 °C), what volume would 2.00 moles of oxygen gas occupy? The gas constant is 8.31
Answer:
44.8 L
Explanation:
Ideal Gas Equation -
i.e.,
PV = nRT
where,
P = pressure
V = volume
n = moles
R = universal gas constant
T = temperature
Using the information given in the question, Volume of the gas can be calculated -
P = 101.3 kPa
V = ?
n = 2.00 moles
R = 8.31
T = 0 degree C = 273.15 K
Using the above data, and putting the data in the respective formula -
PV = nRT
101.3 kPa * V = 2.00 moles * 8.31 * 273.15 K
V = 44.8 L
Hence, the volume of the given gas = 44.8 L
3. The hydroxide-ion, [OH-], concentration in a detergent solution is 1.0 x 10-3 M. What is [H+] concentration in the detergent solution?
A) 1.0 x 10^-11 M.
B) 1.0 x 10^-9 M.
C) 1.0 M
D) 0.001 M
Answer:
c
Explanation:
h
Write a balanced equation for each reaction. KOH(aq) + H3PO4,(aq)
Answer:
3 KOH(aq) + H3PO4(aq) = K3PO4(aq) + 3 H2O
Explanation:
Which of the following is NOT a compound?
Water
Ammonia
Gold
Salt
The gold is not the compound.
The information related to the compound is as follows
It is the substance that contains the same type of molecules having 2 or more elements. It includes water, ammonia, salt, methane, carbon dioxide etc.In this, the elements should be bonded together.Therefore we can say that gold is not the compound.
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PLEASE HELP!! 15 POINTS!
What could the fourth quantum number of a 2s^2 electron be?
Answer:
option D
Explanation:
first quantum number of a 2s2
n = 2
second quantum number of a 2s2
l = 0 to n-1
l = 0, 1
For s orbital
l = 0
third quantum number of a 2s2
ml = - l to +l
ml = 0
fourth quantum number of a 2s2 electron be
?½ = spin down
½ = spin up
2s2 has 2 electrons 1 spin down and 1 spin up (starts with spin down)
ms = +1/2
Answer:
+1/2
Explanation:
please help me this is due very soon
Answer:
the answer is a because thermal energy is heat and the question said that is not a factor of thermal energy so A does not refer to heat
The molecular weight of PCl3 is blank
amu.
Answer:
Yes you are correct
Explanation:
But the spelling is black amu
BRAINLIEST WILL BE GIVEN, PLZ HELP + 15 PTS
Which properties are characteristic of true solutions? (Select all that apply.)
The light beam is unaffected.
The particles are larger than 10 -8 cm.
The particles are dissolved.
The particles are suspended indefinitely.
Answer:
The correct answer is the last option
Explanation:
No links.
Calculate the pH and pOH of each solution.
a) [H + ] = 1.7 x 10 -8M
b) [H + ] = 1.0 x 10 -7M
Explanation:
first find the value of Ph
from Ph= -log[H+]
ph=-log[1.7x10^-8]=7.769
find Poh from 14=ph+poh
14=7.769+poh
Poh=6.231 part a
for part b the same as part a from the above procedure
A student makes several observations about a plece of iron. Which observation describes a chemical property of the Iron?
Answer:rust
Explanation:
The specific heat of nickel is 0.445 J/g degree Celsius. How much heat is required to heat a 168 gram piece of nickel from 15.2 degrees Celsius to 43.6 degrees Celsius?
When is the mole ratio from a balanced chemical reaction not needed in a calculation
Answer:16
Explanation:
Forested land in the area was cleared to make several building lots. Trees were left on the outskirts of each lot. This is a picture of
one lot that has not sold, so there has been no house built. If the lot does not sell, predict how this area will look in another five
years.
A)
The land will be forested once again.
B)
The plot of land will be covered with grasses and flowers.
C)
The weeds will be replaced by woody shrubs and some small trees.
Answer:
C
Explanation:
The weeds will be replaced by woody shrubs and some small trees.
If the forest land is cleared, it is hard to construct a forest again. The cleared land will grow as grass land then if there is no constructions or buildings fills the land. Hence, option B is correct.
What is forstation?Forestation is the process of formation of forests and dense growth of trees and other kinds of plants. Forests are example of ecosystems and wide variety of plant species and animals are living there.
Nowadays, deforestation is common for the selfish purposes of man to buildups their own amenities so that, many more plants and animals are on the edge of extinction.
There are naturally made forests as well as man made forests. It was results of hard working that to form a forest with all its atmosphere and biodiversity will take longer time. It will not happen within just five years.
Thus, if the forest land is cleared, the empty ground may fill with grasses and flower plants. Hence option B is correct.
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In the image of the billiard table below, a cue ball is about to be struck and pushed toward the other balls
When the cue ball collides with the other balls, it will slow down and the other balls will be set in motion. Which statements best
describes why?
OA. The cue ball loses all of its kinetic energy, and the other balls gain some kinetic energy
OB. The cue ball loses all of its kinetic energy, and the other balls gain some potential energy
OC. The cue ball loses some of its potential energy, and the other balls gain some kinetic energy
OD. The cue ball loses some kinetic energy, and the other balls gain some kinetic energy
Answer:
c
Explanation:
Which forces of attraction do you think are stronger, the attractions that are broken or the new attractions that are formed? Explain your reasoning. *
Answer: The forces of attraction are stronger in new attractions that are formed.
Explanation:
When a chemical reaction takes place between two or more different compounds then less reactive substance is displaced by the more reactive substance.
During this process, when bonds are broken between the reactants then it means the force of attraction is less stronger. The formation of new compounds occur because force of attraction is more in these new substances due to which its atoms come closer to each other.
Thus, we can conclude that forces of attraction are stronger in new attractions that are formed.
Type the correct answer in each box.
Balance the equation.
_____SiO2 + ______CaC2 → _____Si + _______CaO + _____CO2
The balanced equation of the given reaction is as follows: 5SiO2 + 2CaC2 → 5Si + 2CaO + 4CO2.
How is an equation balanced?A chemical equation is said to be balanced when the number of atoms of each element on both sides of the equation is the same.
According to this question, a chemical reaction between quartz and calcium chloride is given to produce silicon, calcium oxide and carbon dioxide.
The balanced equation that represents an equal number of atoms on both sides is as follows:
5SiO2 + 2CaC2 → 5Si + 2CaO + 4CO2
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A ship is sailing at a speed of 5 km/hr. What distance has it covered, 2 hours after it left the port?
Answer:
10km
Explanation:
Answer:
[tex]\boxed {\boxed {\sf 10 \ kilometers}}[/tex]
Explanation:
Distance is the product of speed and time.
[tex]d=s \times t[/tex]
The speed of the ship is 5 kilometers per hour. The time is 2 hours.
s= 5 km/hr t= 2 hrSubstitute the values into the formula.
[tex]d= 5 \ km/hr * 2 \ hr[/tex]
Multiply. Note that the hours will cancel each other out.
[tex]d= 5 \ km * 2 \\d=10 \ km[/tex]
The ship covers a distance of 10 kilometers.
What are these means in Periodic Table;
Group
Period
Block
Stem cells can differentiate into how many types of body cells?
Convert 0.64 moles of table salt (NaCl) to grams
Answer:
0.64 moles of table salt = 37.44 grams of table salt
Explanation:
mNaCl = 0.64 x (23 + 35.5) = 37.44 grams
Which is an example of kinetic energy?
A. A stretched rubber band
B. Wind
C. Water in a reservoir
D. Natural gas
E. An object suspended above the ground
Answer:
B. Wind
Explanation:
Kinetic energy is moving
2
In the movie, Tim says that Saturn's rings refract light to
produce colors. What does this mean?
A They emit light
B They bend and reflect light
CThey absorb all light
D They block light
Answer:
It would be B they bend to reflect light
Heeelllpp !!
What system is sealed and will not release any gases from a chemical reaction?
Answer: closed system
Explanation:
In general, what happens when a subscript is found
outside of parentheses?
Answer:
you multiply it by the other subscripts in the parenthesis.
Explanation:
What is the molar mass of Ca(NO3)2?
a 102.2 g/mol
b 134.1 g/mol
c O 164.1 g/mol
d 0 204.2 g/mol
Answer:
C.164.1g/mol
Explanation:
40+14×2+16×6
164
The molar mass of Ca(NO3)2 is 164.1 g/mol.
What is Calcium nitrate?
Calcium nitrate, also called Norgessalpeter (Norwegian salpeter), is an inorganic compound with the formula Ca(NO3)2(H2O)x. The anhydrous compound, which is rarely encountered, absorbs moisture from the air to give the tetrahydrate. Both anhydrous and hydrated forms are colourless salts. Calcium nitrate is mainly used as a component in fertilizers, but it has other applications. Nitrocalcite is the name for a mineral which is a hydrated calcium nitrate that forms as an efflorescence where manure contacts concrete or limestone in a dry environment as in stables or caverns. A variety of related salts are known including calcium ammonium nitrate decahydrate and calcium potassium nitrate decahydrate.
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HELP A #QUEEN OUT !!!!!!
Select the correct answer.
Which reaction is a decomposition reaction?
A.
2KClO3 → 2KCl + 3O2
B.
4Na + O2 → 2Na2O
C.
ZnS + 3O2 → 2ZnO + 2SO2
D.
2NaBr + CaF2 → 2NaF + CaBr2
Answer: 2KClO3 → 2KCl + 3O2
Explanation: it's the only one that was broken down into more parts than the start, the rest were simply reseperated
this one : 1 → 2
b : 1 + 1 = 2
c : xy+ wz → wy + xz
d : qwer +tyuio → qwui + tyero
ALSO I got it right