Answer:
11.81
Explanation:
We'll begin by writing the balanced dissociation equation for KOH. This is given below:
KOH —> K+ + OH-
Next, we shall determine the concentration of Hydroxide ion, [OH-]. This is illustrated below:
From the balanced equation above,
We can see that 1 mole of KOH produced 1 mole of OH-.
Therefore, 6.50x10^-3 M KOH will also produce 6.50x10^-3 M OH-.
Next, we shall determine the pOH of the solution. This is illustrated below:
pOH = –Log [OH-]
[OH-] = 6.50x10^-3 M
pOH = –Log 6.50x10^-3
pOH = 2.19
Finally, we can determine the pH of the solution as follow:
pH + pOH = 14
pOH = 2.19
pH + 2.19 = 14
Collect like terms
pH = 14 – 2.19
pH = 11.81
Therefore, the pH of the solution is 11.81
The pH of a 6.50 x 10-3 M KOH solution is 11.81 which is alkaline.
pH is a measure of how acidic or basic a solution is. Ph has a range from 0 to 14. pHs with less than 7 show acidity, while a pH of greater than 7 indicates a base/ alkalinity. , pH of 7 shows the solution is neutral.
KOH is a strong base, Upon dissociation,it gives
KOH -> K⁺ + OH⁻
Here, 1 mole of KOH produced 1 mole of OH-.
Therefore, 6.50 x 10-3 M KOH will prodce 6.50 x 10-3 M H
Now, we first determine the pOH of the solution with the equation:
pOH = –Log [OH-]
[OH-] = 6.50x10^-3 M
pOH = –Log 6.50x10^-3
pOH = 2.19
Now, we know that
pH + pOH = 14
Having gotten that
pOH = 2.19,
pH + 2.19 = 14
pH = 14 – 2.19
pH = 11.81
Therefore, the pH of the KOH solution is 11.81 which is alkaline.
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Students are comparing the physical properties of sugar water, salt water,and plain water,including the affects of thermal energy. What safety equipment is needed?
A-Graduated Cylinder and gloves
B-safety goggles and thermometer
C-thermometer and hot plate
D-safety goggles and gloves
Answer:
D
Explanation:
The safety equipment that is needed when your doing a science experiment you need a safety goggles and gloves.
a _____ is substance in which one or more atoms have the same number of protons (I.e. the same atomic number)
Answer: Element
Explanation:
Answer: a proton is substance in which one or more atoms have the same number of protons
Boiling water is an example of what type of what type of thermal energy transfer?
convection
conduction
insulation
radiation
Answer:
Conduction
Hot water is conducting heat because it is moving
Boiling water is an example of conduction heat transfer (option B).
What is heat transfer?Heat is one of the various forms in which energy can exist. Heat transfers with or without medium from one place to another.
There are three ways in which heat is transferred in the environment;
ConductionConvectionRadiationConduction is the conveying of heat or electricity through a solid material such as the material used to boil water in this case. Therefore, option B is correct.
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The process by which complex compounds are broken down by enzymes and by which many organic alcohols are formed is called
Answer:
fermentation
Explanation:
Blast furnaces extra pure iron from the Iron(IIl)oxide in iron ore in a two step sequence. In the first step, carbon and oxygen react to form carbon monoxide:
2C(s)+O2(g) arrow 2CO(g)
In the second step, iron(lll) oxide and carbon monoxide react to form Iron and carbon dioxide:
Fe203(s) + 3CO(g) arrow 2Fe(s)+ 3CO2(g)
Suppose the yield of the first step is 71.% and the yield of the second step is 72.%. Calculate the mass of oxygen required to make 7.0 kg of iron.
Be sure your answer has a unit symbol, if needed, and is rounded to 2 significant digits.
Answer:
5.9 kg
Explanation:
We must work backwards from the second step to work out the mass of oxygen.
1. Second step
Mᵣ: 55.84
Fe₂O₃ + 3CO ⟶ 2Fe + 3CO₂
m/kg: 7.0
(a) Moles of Fe
[tex]\text{Moles of FeO} = \text{7000 g Fe} \times \dfrac{\text{1 mol Fe}}{\text{55.84 g Fe}} = \text{125 mol Fe}[/tex]
(b) Moles of CO
[tex]\text{Moles of CO} = \text{125 mol Fe} \times \dfrac{\text{3 mol CO}}{\text{2 mol Fe}} = \text{188 mol CO}[/tex]
However, this is the theoretical yield.
The actual yield is 72. %.
We need more CO and Fe₂O₃ to get the theoretical yield of Fe.
(c) Percent yield
[tex]\begin{array}{rcl}\text{Percent yield} &=& \dfrac{\text{ actual yield}}{\text{ theoretical yield}} \times 100 \, \%\\\\ 72. \, \% & = & \dfrac{\text{188 mol}}{\text{actual yield}} \times 100 \,\%\\\\0.72 &= &\dfrac{\text{188 mol}}{\text{actual yield}}\\\\\text{Actual yield} & = & \dfrac{\text{188 mol}}{0.72}\\& = & \textbf{261 mol}\\\\\end{array}[/tex]
We must use 261 mol of CO to get 7.0 kg of Fe.
2. First step
Mᵣ: 32.00
2C + O₂ ⟶ 2CO
n/mol: 261
(a) Moles of O₂
[tex]\text{Moles of O}_{2} = \text{261 mol CO} \times \dfrac{\text{1 mol O}_{2}}{\text{2 mol CO}} = \text{131 mol O}_{2}[/tex]
(b) Mass of O₂
[tex]\text{Mass of O}_{2}= \text{131 mol O }_{2} \times \dfrac{\text{32.00 g O}_{2}}{\text{1 mol O}_{2}} = \text{4180 g O}_{2}[/tex]
However, this is the theoretical yield.
The actual yield is 71. %.
We need more C and O₂ to get the theoretical yield of CO.
(c) Percent yield
[tex]\begin{array}{rcl}71. \, \% & = & \dfrac{\text{188 mol}}{\text{actual yield}} \times 100 \,\%\\\\0.71 &= &\dfrac{\text{4180 g}}{\text{actual yield}}\\\\\text{Actual yield} & = & \dfrac{\text{4180 g}}{0.71}\\\\& = & \text{5900 g}\\& = & \textbf{5.9 kg}\\\end{array}[/tex]
We need 5.9 kg of O₂ to produce 7.0 kg of Fe.
What is the volume of 9.5 g fluorine gas, F2, at STP?
Answer:
5.6L
Explanation:
At STP, the pressure and temperature of an ideal gas is
P = 1 atm
T = 273.15k
Volume =?
Mass = 9.5g
From ideal gas equation,
PV = nRT
P = pressure
V = volume
n = number of moles
R = ideal gas constant =0.082J/mol.K
T = temperature of the ideal gas
Number of moles = mass / molar mass
Molar mass of F2 = 37.99g/mol
Number of moles = mass / molar mass
Number of moles = 9.5 / 37.99
Number of moles = 0.25moles
PV = nRT
V = nRT/ P
V = (0.25 × 0.082 × 273.15) / 1
V = 5.599L = 5.6L
The volume of the gas is 5.6L
What is the wavelength of a light frequency 7.21x10^14Hz
Answer:
6.0 x 105
Explanation:
Answer:6.0 x l05
Explanation:
Describe how alleles and genes are related.
Answer:
A gene is a stretch of DNA or RNA that determines a certain trait. Genes mutate and can take two or more alternative forms; an allele is one of these forms of a gene. Chromosomes occur in pairs so organisms have two alleles for each gene one allele in each chromosome in the pair.
When a substance changes from a liquid to a solid, it has reached its _____ point
Answer:
The temperature at which a substance changes from the liq- uid state to the solid state is called the freezing point. The freez- ing point of the liquid state of a substance is the same temperature as the melting point of the solid state. For example, solid water melts at 0°C and liquid water freezes at 0°C.
Explanation:
A student investigates a pure metal, X. The student takes a 100.0 g piece of metal X, heats it
to 500.0°C, then places it on a 1000.0 g block of ice at 0.0°C. The ice partially melts, and
the final temperature of the metal, ice, and melted water is 0.0°C. The student calculates the
experimental value of the specific heat capacity of metal X and records it as
0.90 J/(g • °C).
(C) Calculate the magnitude of the energy change of metal X during the experiment.
(d) Calculate the mass of ice melted by metal X. (The enthalpy of fusion of ice is 330J/g.
(e) A student claims that the energy transferred to the ice breaks the polar-covalent O-H
bonds found between atoms within water molecules. Do you agree or disagree with this
claim? Justify your answer.
Answer: The answer would be D
Explanation:
The magnitude of the energy change of metal X during the experiment is 6500 J, and the mass of ice melted by metal X is 19.7 g and the claim of the student is correct.
What are changes in ice?The magnitude of energy change of metal is equal to the mass of metal x specific heat capacity of metal x temp. difference
= 100 g x 0.13 J / ( g- oC) x (500 - 0) oC
= 6500 J
According to the question, the enthalpy of the fusion of ice is 330 J / g
Thus 330 J heat is used to melt 1 g of ice
So 6500 J heat is used to melt = 1 x (6500 / 330) = 19.7 g ice
Although hydrogen bonds can form in both a solid and a liquid state, they are more stronger in the solid state. In order to partially dissolve its hydrogen bonds and turn solid ice into liquid water, whatever heat is applied to it is therefore used.
Therefore, the student's assertion is true.
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In a nuclear reaction, which of the following must be conserved?
A. energy
B. mass
C. charge
D. the number of electrons
Answer:
A. Energy must be conserved in a nuclear reaction
Explanation:
Answer:
Explanation:
In a nuclear reaction, which of the following must be conserved?
A. Energy
Which sequence represents the relationship between temperature and volume as explained by the kinetic-molecular theory?
higher temperature → more kinetic energy → more space between particles – higher volume
higher temperature → less kinetic energy → less space between particles higher volume
o higher temperature → more kinetic energy → less space between particles → lower volume
higher temperature → less kinetic energy → more space between particles lower volume
Answer:
higher temperature → less kinetic energy → less space between particles higher volume
Explanation:
According to Reference Table Adv-8, which of the following is the strongest Brönsted-Lowry acid?
1.HS-
2.H2S
3.HNO2
4.HNO3
Answer:
HNO3
Explanation:
The ability of an acid to act as a Brownstead-Lowry acid depends on it's proton donation ability.
A Brownstead-Lowry acid is a specie that donates hydrogen ions in solution.
Considering all the chemical species listed among the options, HNO3 has the greatest hydrogen donation ability. It then follows that HNO3 is the strongest Brownstead-Lowry acid among the species listed.
PLEASE HELP :)
which type of reaction is shown in the diagram
a. fusion, because the reaction released energy?
b.fission, because the reaction absorbed energy
c.fusion, because the reaction formed lighter nuclei
d.fission,because the reaction formed heavier nuclei
Answer:
b.fission, because the reaction absorbed energy
Explanation:
The reaction is shown in the diagram is fission. because the reaction absorbed energy. Therefore, option B is correct.
What is fission ?The process of nuclear fission involves the splitting of an atom's nucleus into two or more smaller nuclei. Even by the energetic standards of radioactive decay, the fission process releases a very high quantity of energy and frequently results in gamma photons.
By dissolving large, heavy atoms, like uranium, into smaller ones, like iodine, caesium, strontium, xenon, and barium, to name just a few, fission produces energy. However, fusion involves joining light atoms, such as the deuterium and tritium isotopes of hydrogen, to create the heavier helium.
Nuclear fission is used by all nuclear power plants, and uranium atoms are typically used in nuclear power plants. A neutron splits a uranium atom when it collides with it during nuclear fission, releasing a significant quantity of energy.
Thus, option B is correct.
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What is the volume of solution (in mL) produced when 91.80g of Mg(OH)2 are used
to produce a 0.7M solution? Record your answer to 1 decimal places.
Answer: The volume of solution is 2248 ml
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.
[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]
where,
n = moles of solute
[tex]V_s[/tex] = volume of solution in ml
moles of [tex]Mg(OH)_2[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{91.80g}{58.32g/mol}=1.574mol[/tex]
Now put all the given values in the formula of molality, we get
[tex]0.7=\frac{1.574\times 1000}{V_s}[/tex]
[tex]V_s=\frac{1.574\times 1000}{0.7}=2248ml[/tex]
Therefore, the volume of solution is 2248 ml
Which statements correctly describe the rock cycle? Check all that apply.
Rocks are preserved through the process.
Rocks change from one type to another.
Different rock groups are interrelated.
Rocks change from one type to another in a specific order.
Environmental conditions influence a change in rock type.
Answer: I italicize for checking
Rocks are preserved through the process.Rocks change from one type to another.Different rock groups are interrelated.Rocks change from one type to another in a specific order.Environmental conditions influence a change in rock type.
Explanation:
Rocks are preserved, as in you can't destroy them completely, but no, they don't stay the same they change.
how does the Doppler effect related to the universal expanding?
Correct name of the compound
Answer:
Calcium Nitride
Explanation:
what is the shortest half life
Answer:
Hey!
Your answer is element A
Explanation:
Using the graph, the element A's emission of radioactive particles ends approximately after 6 years...
A HALF-LIFE IS "HALF" OF THAT TIME PERIOD!
So if the radiation goes for 6 years the half-life is 6 divided by two which gives you 3 years!
The rest however have a longer half-life...
Because they all end at 14 yrs so their half-life in 7 years!
HOPE THIS HELPS!!
What was the purpose of the Apollo space missions?
to collect rock samples from Mars
to land on Saturn
to collect rock samples from the moon
to land on Jupiter
Answer:
i agree with the above to collect rock samples
Explanation:
took test got 100 best of luck
The purpose of the Apollo space missions was to to collect rock samples from the moon.
What is moon?
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of Australia).The Moon is a planetary-mass object with a differentiated rocky body, making it a satellite planet under the geophysical definitions of the term and larger than all known dwarf planets of the Solar System.
It lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's at 0.1654 g, with Jupiter's moon Io being the only satellite in the Solar System known to have a higher surface gravity and density.
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What name is given to any chemical which increase the rate of a chemical reaction
Answer:
It is called catalyst.
Answer:
A catalyst
Explanation:
is a substance that can alter the rate of a chemical reaction. Catalysts can be successfully used to increase the rate of a chemical reaction.
A student observes the chemical process described by this equation:
4Al + 3O2 → 2Al2O3
How does the mass of the new substance compare to the total mass of the starting materials?
Answer:
Both are equal
Explanation:
Mass of starting material i.e Aluminium is [tex]4.480 * 10^{-23}[/tex] grams
The weight of oxygen is [tex]2.65 * 10^{-23}[/tex]
There are 4 atoms of aluminium and 3 atoms of oxygen
Thus, the total mass of starting material is
[tex]4 *[/tex] mass of one atom of aluminium [tex]+ 6 *[/tex] mass of one atom of oxygen
[tex]4 * 4.480 * 10^{-23} + 6* 2.65 * 10^{-23}[/tex]
[tex]35.1 * 10^{-23}[/tex] grams
Mass of new substance is also equal to
[tex]4 *[/tex] mass of one atom of aluminium [tex]+ 6 *[/tex] mass of one atom of oxygen
[tex]4 * 4.480 * 10^{-23} + 6* 2.65 * 10^{-23}[/tex]
[tex]35.1 * 10^{-23}[/tex] grams
If the temperature of a gas decreases at constant volume which of the following would occur
Answer:
I need the things after "which of the following would occur".
Explanation:
If you were to maintain a constant volume while decreasing pressure, the temperature would also have to decrease. This is Boyle's law.
help asap plzzz! Which of the following diagrams is the correct electron dot diagram for S?
Answer:
A.
Explanation:
Sulfur has 6 valence electrons, therefore has 6 dots.
- Hope that helps! Please let me know if you need further explanation.
The correct option is A.
What is a dot diagram?
A Lewis electron dot diagram (or electron dot diagram, or a Lewis diagram, or a Lewis structure) is a representation of the valence electrons of an atom that uses dots around the symbol of the element. The number of dots equals the number of valence electrons in the atom.
Why do we use electron dot diagrams?These diagrams are helpful because they allow us to show how atoms are connected, and when coupled with Valence Shell Electron Repulsion Theory (VSEPR), we can use Lewis structures to predict the shape of the molecule.
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You take a very hot block of metal on top of a cold block of metal. What will
happen to the temperature of both blocks over time?
Answer:
They will both cool down overtime
Explanation:
Once you put something that is hot on something that is cold. They will both be hot, but overtime they will cool down. It can't stay hot forever.
Answer:
Hey!
Your answer is that one block of metal (the cold one) would heat up a bit whilst the other block (the hot one) would cool down...This is because of the metal's CONDUCTIVITY!
Explanation:
Eventually you would measure the temperature of both blocks and they will reach the same temperature. After this they will naturally cool down...
HOPE THIS HELPS!!
26.9 g of solid lithium is combined with 20.0 grams of nitrogen gas. .
When the reaction is complete, an actual yield of 32.5 grams of solid product is produced.
Need to know how to do it, please help me soon!
Answer:
The theoretical yield of
Li
3
N
is
20.9 g
.
Explanation:
Balanced Equation
6Li(s)
+
N
2
(
g
)
→
2Li
3
N(s)
In order to determine the theoretical yield, we must first find the limiting reactant (reagent), which will determine the greatest possible amount of product that can be produced.
Molar Masses
Li
:
6.941 g/mol
N
2
:
(
2
×
14.007
g/mol
)
=
28.014 g/mol
Li
3
N
:
(
3
×
6.941
g/mol Li
)
+
(
1
×
14.007
g/mol N
)
=
34.83 g/mol Li
3
N
Limiting Reactant
Divide the mass of each reactant by its molar mass, then multiply times the mole ratio from the balanced equation with the product on top and the reactant on bottom, then multiply times the molar mass of
Li
3
N
.
Lithium
12.5
g Li
×
1
mol Li
6.941
g Li
×
2
mol Li
3
N
6
mol Li
×
34.83
g Li
3
N
1
mol Li
3
N
=
20.9 g Li
3
N
Nitrogen Gas
34.1
g N
2
×
1
mol N
2
28.014
g N
2
×
2
mol Li
3
N
1
mol N
2
×
34.83
g Li
3
N
1
mol Li
3
N
=
84.8 g Li
3
N
Lithium produces less lithium nitride than nitrogen gas. Therefore, the limiting reactant is lithium, and the theoretical yield of lithium nitride is
20.9 g
.
Explanation:
Why did the United States government set aside land for the first national parks?
A.
They wanted to settle the west as quickly as possible.
B.
They worried people would destroy the animals and land.
C.
They worried Native Americans wouldn’t have anywhere to go.
D.
They wanted to make sure all citizens would get a piece of land.
Answer:
b
Explanation:
hope it helps
Please help I don’t understand
Select the correct answer.
Which action reflects irresponsible lab safety behavior?
A.
not wearing goggles when breaking a rock with a hammer
B.
not shaking hands with your lab partner after a successful experiment
C.
not chatting with others while mixing two reactive chemicals
D.
not sharing findings and recordings with the general public
E.
not using scientific tools while making crucial observations
Answer:
A. not wearing goggles when breaking a rock with a hammer
Explanation:
You could get extremely hurt if you are not wearing goggles while doing lab work.
The action that reflects irresponsible lab safety behavior is not wearing goggles when breaking a rock with a hammer. Thus, the correct option for this question is A.
What are Lab safety behaviors?Lab safety behaviors may be defined as those actions and habits that are persistently taken by individuals in order to maintain discipline and safety on their own. Some of the lab safety behaviors are as follows:
Avoid skin and eye contact with all chemicals by wearing gloves and goggles.Follow an accurate protocol during an experiment. Beware of all safety showers, eye washers, and fire extinguishers. Avoid eating, drinking, and unnecessary talking in the lab.Never smell or inhale laboratory chemicals.Some of the lab safety behaviors also include not shaking hands with your lab partner after a successful experiment, not sharing findings and recordings with the general public, etc. This is because these are some private sources of information.
Therefore, the action that reflects irresponsible lab safety behavior is not wearing goggles when breaking a rock with a hammer. Thus, the correct option for this question is A.
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If is known how deep the water table in an area is, it is known how deep to dig to reach
Pores
The unsaturated zone
Solid rock
Groundwater
Answer:
grond water
Explanation:
