Answer:
E = hV
Explanation:
Hello,
Photo electric effect theory was borne out the the confusing if light was either a particle or a wave. However Albert Einstein came up with a theory that light was a particle and each particle carry a certain amount of energy referred to as photons.
He used Max Planck's idea and theorized that since light is made up of photon, when each photon comes in contact with the surface of a metal, the energy is transferred to the electron.
E = hv
E = energy of the photons
h = Planck's constant = 6.626×10⁻³⁴Js
v = frequency of the photon in Hz
Answer:
B
Explanation:
If the reaction CH4(g) O2(g) <--> CO2(g) 2H2O(g) is in equilibrium, what is the effect of adding a catalyst
Answer:
Adding a catalyst increases the speed of the reaction.
Explanation:
The catalyst increases the reaction rate since what it does is to consume the reagents more easily in order to obtain the products faster.
The catalysts DO NOT ALTER THE QUANTITY OF PRODUCTS OR REAGENTS, that is to say that they do not add grams nor do they intervene in the masses of the chemical compounds of the reaction, they only speed up the procedure.
What is a heterogeneous mixture?
Answer:
The type of mixture whose components are seen through our naked eyes is known as heterogeneous mixture. it is a mixture of small constituent parts of substances.
for eg, mixture of sand and sugar.
hope it helps..
A combination reaction is given below: 3A 2B --5C If compound A has a molar mass of 159.7 g/mole and compound C has a molar mass of 57.6 g/mole, how many grams of compound C will be produced from 26.96 grams of compound A and excess compound B
Answer:
16.2 g
Explanation:
Step 1: Write the balanced reaction
3 A + 2 B ⇒ 5 C
Step 2: Calculate the moles corresponding to 26.96 g of A
The molar mass of A is 159.7 g/mol.
[tex]26.96 g \times \frac{1mol}{159.7g} = 0.1688 mol[/tex]
Step 3: Calculate the moles of C produced from 0.1688 moles of A
The molar ratio of A to C is 3:5. The moles of C produced are 5/3 × 0.1688 mol = 0.2813 mol.
Step 4: Calculate the mass corresponding to 0.2813 moles of C
The molar mass of C is 57.6 g/mol.
[tex]0.2813 mol \times \frac{57.6g}{mol} = 16.2 g[/tex]
When an aqueous solution of AgNO3 is electrolyzed, a gas is observed to form at the anode. The gas is
Answer:
Oxygen
Explanation:
First, list out all the ions in the aqueous solution:
Ag+, NO3-
H+, OH-
In the anode, the substance lose electrons to undergo oxidation.
From the 4 ions, only OH- can lose electrons to form water and oxygen,
4OH- ---> O2 + 2H2O + 4e-
While others tend to gain electrons to form new substances instead (they undergo reduction).
Oxygen is the gas produced.
The gas should be treated as the Oxygen.
Identification of the gas:here First, list out all the ions that should be in the aqueous solution:
Ag+, NO3-
H+, OH-
In the anode, the substance loses electrons for undergoing oxidation.
From the 4 ions, only OH- can lose electrons to form water and oxygen.
The balanced chemical equation be like
4OH- ---> O2 + 2H2O + 4e-
While on the other hand, it tend to gain electrons to create new substances. Therefore, Oxygen is the gas produced.
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Which example describes a use for gemstones?
fabrics
plastics
drill bits
paper clips
Answer:
Drill bits
Explanation:
Gemstones such as diamonds are used in drill bits because of their hardness.
They are a 10 on the Mohs scale of hardness, which runs from 0 to 10.
Drill bits are produced from gemstones due to their hardness.
What are gemstones?Gemstones are the name given to pieces of minerals that can be cut and polished valuable accessories.
Gemstones such as diamonds are used in drill bits because of their hardness.
Examples of drill bitsBrad Point Drill BitsMasonry Drill BitsRivet Drill BitsSpade Drill BitsThus, drill bits are produced using gemstones.
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Write a balanced equation for the combustion of liquid methanol in air, assuming H2O(g) as a product.
Answer:
2 CH₃OH + 3 O₂ ⇒ 2 CO₂ + 4 H₂O
Explanation:
Methanol is CH₃OH. Oxygen is O₂. A combustion produces CO₂ and H₂O. Create an equation using this information and balance.
CH₃OH + O₂ ⇒ CO₂ + H₂O
2 CH₃OH + 3 O₂ ⇒ 2 CO₂ + 4 H₂O
The balanced equation for the combustion of liquid methanol in air, assuming H2O(g) as a product is
CH₃OH(l) + O₂(g) → CO₂(g) + H₂O(g)
From the question,
We are to write a balanced equation for the combustion of liquid methanol in air.
The combustion of liquid methanol in air is the reaction between methanol (CH₃OH) and oxygen (O₂). The reaction yields carbon(IV) oxide and water.
Now, for the balanced equation for the combustion of liquid methanol in air
The balanced chemical equation is
CH₃OH(l) + O₂(g) → CO₂(g) + H₂O(g)
Hence, the balanced equation for the combustion of liquid methanol in air, assuming H2O(g) as a product is CH₃OH(l) + O₂(g) → CO₂(g) + H₂O(g)
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A temperature of 41 Fahrenheit is the same as
Answer:
5 degrees Celsius.
Explanation:
Temperature measures the average kinetic energy of particles of the substances. Therefore a temperature of 41 Fahrenheit is the same as 5 degree Celsius
What is temperature?
Temperature is used to measure degree or intensity of heat of a particular substance. Temperature is measured by an instrument called thermometer.
Temperature can be measured in degree celsius °c, Kelvin k or in Fahrenheit. Temperature is a physical quantity. Heat always flow from higher temperature source to lower temperature source.
We can convert these units of temperature into one another. The relationship between degree Celsius and Fahrenheit can be expressed as:
°C={5(°F-32)}÷9
Substituting given values in above equation
°C= {5(41-32)}÷9
°C= 5°C
Therefore a temperature of 41 Fahrenheit is the same as 5 degree Celsius
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Which process is endothermic?a)b)c)d)The evaporation of water from the skin.The burning of candle wax.The oxidation of iron in a chemical hand warmer.The combustion of natural gas in a stove
Answer:
The answer is option a. The evaporation of water from the skin
Explanation:
An endothermic reaction is any synthetic reaction that retains heat from its environment. The ingested energy gives the enactment energy to the reaction to happen.
No new bonds formed, no bonds broken in this example. water molecules go from liquid to vapour (gas ), intermolecular bond exist between polar (-OH) molecules and energy is required to break these bonds during the change from liquid to gas. So, it is endothermic .
Remaining three above examples are exothermic. combustion of gas releases energy(exothermic). burninig of the candle exothermic because the energy released from the oxygen into carbon dioxide and water.oxidation of iron also exothermic
Using the volumes of EDTA solution you just entered and the corresponding dry unknown sample masses entered earlier, calculate the percent mass of calcium carbonate in the unknown sample mixture.
Enter the calculated percent mass of calcium carbonate in the dry unknown sample for each of the 3 acceptable trials.
Be sure to enter your mass percentages to the correct number of significant digits and in the corresponding order that you entered your masses of your dry unknown samples and volumes of your EDTA previously. The dry unknown sample mass you entered for entry #1 below should correspond to the percent mass of calcium carbonate you enter for entry #1 here.
Trial #: Mass (Grams):
#1: 0.015
#2: 0.015
#3: 0.015
Volume (mL)
#1: 16.4
#2: 15.00
#3: 18.70
Molarity of EDTA Solution: 0.0675
Answer:
#1
Explanation:
molarity of EDTA solution 0.0675
no1
A voltaic cell is created by using a copper cathode and a magnesium anode. The cathode is immersed in a solution of Cu2 ions, and the anode is immersed in a solution of Mg2 ions. A salt bridge of Na2SO4 is also used. What happens to the ions in the salt bridge as the reaction proceeds
Answer:
As the reaction proceeds in the given voltaic cell, the Na₂SO₄ present in the salt bridge will dissociate into Na⁺ and SO₄²⁻ ions. As the copper ions in the solution are being deposited on the copper cathode as neutral copper atoms, the solution will become more negative, therefore the Na⁺ ions in the salt bridge will migrate into the the solution in order to maintain electrical neutrality. At the anode, as the Mg metal dissolve into the solution as Mg⁺² ions, the solution will tend to become more positive. Therefore, the SO₄²⁻ ions present in the salt bridge will migrate into the solution in order to maintain electrical neutrality.
Explanation:
A voltaic or galvanic cell is an example of an electrochemical cell.
An electrochemical cell is a device that produces an electric current from chemical reactions occuring within it.
Electrochemical cells have two electrodes; the anode and the cathode. The anode is defined as the electrode where oxidation occurs while the cathode is the electrode where reduction occurs.
The voltaic cell uses two different metal electrodes each immersed in an electrolyte solution. The two electrodes are connected to each other by means of a wire which allows the flow of electrons from the anode to the cathode. The electrolytes are connected by means of a salt bridge which is a junction that connects the electrolytic solution in the anode and cathode compartment. The salt bridge usually consists of a strong electrolyte like NaCl, KCl, Na₂SO₄, etc.
The electrolyte in the salt bridge serves two purposes: it completes the circuit by providing a path for electron flow and it maintains electrical neutrality in both solutions by allowing ions to migrate between them.
As the reaction proceeds in the given voltaic cell above, the Na₂SO₄ present in the salt bridge will dissociate into Na⁺ and SO₄²⁻ ions. As the copper ions in the solution are being deposited on the copper cathode as neutral copper atoms, the solution will become more negative, therefore the Na⁺ ions in the salt bridge will migrate into the the solution in order to maintain electrical neutrality. Also, at the anode, as the Mg metal dissolve into the solution as Mg⁺² ions, the solution will tend to become more positive. Therefore, the SO₄²⁻ ions present in the salt bridge will migrate into the solution in order to maintain electrical neutrality.
Temperature farthest from the
initial temperature (22.5°C)
COMPLETE
RETRY
Answer:
The next part is 8.8
Explanation:
You're gonna subtract 31.3 by 22.5 which is 8.8
You're welcome :)
The value of q-cal is 142.8 J in the reaction of magnesium and hydrochloric acid in a different constant pressure calorimeter with a calorimeter constant of 12.75 J/degrees Celsius.
What is calorimeter?A calorimeter is a device that measures the amount of heat in a chemical or physical process.
To calculate the value of q-cal (heat absorbed or released by the calorimeter), we need to use the following equation:
q = C * ΔT
Where q is the heat absorbed or released by the calorimeter, C is the calorimeter constant, and ΔT is the change in temperature.
In this case, we know that the calorimeter constant is 12.75 J/degrees Celsius, the initial temperature is 22.5 degrees Celsius, and the final temperature is 33.7 degrees Celsius.
Therefore, we can calculate ΔT as:
ΔT = final temperature - initial temperature
ΔT = 33.7°C - 22.5°C
ΔT = 11.2°C
Substituting these values into the equation, we get:
q = C * ΔT
q = 12.75 J/°C * 11.2°C
q = 142.8 J
Therefore, the value of q-cal is 142.8 J.
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Your question seems incomplete, the probable complete question is:
Suppose you perform the reaction of magnesium and hydrochloric acid in a different constant pressure calorimeter with a calorimeter constant of 12.75 J/degrees Celsius. The initial temperature in the calorimeter is 22.5 degrees Celsius and the final temperature after the reaction is 33.7 degrees Celsius. What is the value of q-cal?
Calculate the vapor pressure of water above a solution prepared by dissolving 28.5 g of glycerin 1C3H8O32 in 125 g of water at 343 K
Answer:
Vapour pressure of the solution is 223.8mmHg
Explanation:
Based on Raoult's law, vapour pressure of a solution decreases related to the vapour pressure of the pure solvent following the equation:
[tex]P_{solution} = X_{solvent}P_{solvent}^0[/tex]
Where P is vapour pressure and X mole fraction of each related substance.
Vapour pressure of pure water is 233.8mmHg
To find Mole fraction of the solution you need to find moles of glycerin and moles of water, mole fraction of water will be:
[tex]\frac{n_{water}}{n_{water}+n_{glycerin}}[/tex]
Moles of water (Molar mass: 18.02g/mol):
125g × (1mol / 18.02g) = 6.937 moles water
Moles of glycerin (Molar mass: 92.09g/mol):
28.5g × (1mol / 92.09g/mol) = 0.309 moles glycerin
Thus, mole fraction of water, X, is:
[tex]\frac{6.937mol}{6.937mol+0.309mol}[/tex]
= 0.957
Replacing in Raoult's law:
[tex]P_{solution} = 0.957*233.8mmHg[/tex]
P = 223.8mm Hg
Vapour pressure of the solution is 223.8mmHg
Fe(s)+ 2 HC2H3O2(aq) → Fe(C2H3O2)2(aq) + H2(g) Which substance is reduced and which subject is oxidized?
Answer:
- Iron is oxidized from 0 to +2.
- Hydrogen is reduced from +1 to 0.
Explanation:
Hello,
In this case, for the given reaction, we must first indicate the oxidation state of each element (notice that HC2H3O is acetic acid)
[tex]Fe ^0(s)+ 2 H^+(C_2H_3O_2)^-(aq) \rightarrow Fe^{2+}(C_2H_3O_2)_2^-(aq) + H_2^0(g)[/tex]
Thereby, notcing that iron is alone at the beginning, it has zero as its oxidation state, but once the reaction is undergone, it changes to +2, moreover, the displaced hydrogen in the acetic acid is with +1 but after the chemical reaction it becomes alone for which its oxidation state is 0, thereby, we find that:
- Iron is oxidized from 0 to +2.
- Hydrogen is reduced from +1 to 0.
Best regards,
Using GRIGNARDS REAGENT convert methane to ethanol
Answer:
J
Explanation:
Gallium chloride is formed by the reaction of 2.25 L of a 1.50 M solution of HCl according to the following equation: 2Ga 6HCl --> 2GaCl3 3H2 Determine the mass of gallium chloride, in grams, produced. Group of answer choices
Answer:
198.56g of GaCl3
Explanation:
We'll begin by calculating the number of mole HCl in 2.25 L of a 1.50 M solution of HCl. This is illustrated below:
Molarity of HCl = 1.50 M
Volume = 2.25 L
Mole of HCl =..?
Molarity = mole /Volume
1.5 = mole /2.25
Cross multiply
Mole = 1.5 x 2.25
Mole of HCl = 3.375 mole
Next, we shall determine the number of mole Gallium chloride, GaCl3 produced from the reaction. This is shown below:
2Ga + 6HCl —> 2GaCl3 + 3H2
From the balanced equation above,
6 moles of HCl reacted to produce 2 moles of GaCl3.
Therefore, 3.375 mole of HCl will react to produce = (3.375 x 2)/6 = 1.125 mole of GaCl3.
Therefore, 1.125 moles of GaCl3 were produced from the reaction.
Next, we shall convert 1.125 mole of GaCl3 to grams. This is illustrated below:
Molar mass of GaCl3 = 70 + (35.5x3) = 176.5g/mol
Mole of GaCl3 = 1.125 mole
Mass of GaCl3 =..?
Mole = mass /Molar mass
1.125 = mass of GaCl3 /176.5
Cross multiply
Mass of GaCl3 = 1.125 x 176.5
Mass of GaCl3 = 198.56g
Therefore, 198.56g of GaCl3 were produced from the reaction.
For the reaction 2 A - Products, the concentration of A is monitored over time. A graph of [A] versus time was found to be linear, with a negative slope. Select the true statement regarding this reaction.
A) The reaction is first order with respect to A.
B) The reaction is second order with respect to A.
C) The rate constant has a negative value.
D) In 2 The reaction has a half-life equal to k.
E) None of these statements is true.
Answer:
none of these statements is true
according to the question E) None of these statements is true.
What is a concentration in chemistry?The concentration of a chemical substance expresses the amount of a substance present in a mixture. There are many different ways to express concentration. Chemists use the term solute to describe the substance of interest and the term solvent to describe the material in which the solute is dissolved
What is concentration in chemistry units?
Quantitative units of concentration include molarity, molality, mass percentage, parts per thousand, parts per million, and parts per billion.
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Which of the following is an alkali metal?
A. Lithium (LI)
B. Boron (B)
c. Calcium (Ca)
D. Krypton (Kr)
Answer:
lithium is akali metal
Answer:
lithium is an alkali metal as it lies in group 1st in modern perodic table.
How many grams of solid Na2CO3 are required to neutralize exactly 2 liters of an HCI solution of pH 2.0?
Answer:
The answer is 1.06g.
Explanation:
Analysis of question:
1. Identify the information in the question given.
volume of HCl is 2 dm3pH of HCl is 2.02. What the question want?
mass of Na2CO3 is ?(unknown)3. Do calculation.1st-Write a balanced chemical equation:Na2CO3 + 2HCl (arrow) 2NaCl + H20 + CO2
2nd-Determine the molarity of HCl with the value of 2.0.pH= -log[H+]
2.0= -log[H+]
log[H+]= -2.0
[H+]= 10 to the power of negative 2(10-2)
=0.01 mol dm-3
molarity of HCl is 0.01 mol dm-3
3rd-Find the number of moles of HCln=MV
=0.01 mol dm-3 × 2 dm3
=0.02 mol of HCl
4th-Find the second mol of it.Based on the chemical equation,
2.0 mol of HCl reacts with 1.0 mol of Na2CO3
0.02 mol of HCl reacts with 0.01 mol of Na2CO3
Na2CO3>a=1 mol
2HCl>b=2 mol
5th-Find the mass of it.mass= number of mole × molar mass
g=0.01 × [2(23)+ 12+ 3(16)]
g=0.01 × 106
# =1.06 g.
Look at the reaction below and state which direction the reaction would shift: A closed container of water and its vapor at equilibrium. Vapor is added to the system.
Water + Energy <=> Vapor
explain
Answer:
According to Le Chatelier's principle, adding additional reactant to a system will shift the equilibrium to the right, towards the side of the products. ... If we add additional product to a system, the equilibrium will shift to the left, in order to produce more reactants.
calculate the molarity of a solution containing 15.2 grams of nacl dissolved in 2.5 l of solution
Answer:
THE MOLARITY OF THE SOLUTION IS 0.1039 MOL/DM3
Explanation:
Molarity is the number of moles of solute in a given solution,
Molarity in mol / dm3 = Molarity in g/dm3 / Molar mass
Mass = 15.2 g
Volume of solution = 2.5 l
Molar mass of NaCl = (23 + 35.5) = 58.5 g/mol
First, we calculate the molarity in g/dm3
Molarity in g/dm3 = mass /volume
= 15.2 g * 1 L / 2.5 L
=6.08 g /dm3
Hence, we will introduce the values and solve for molarity in mol/dm3
Molarity = 6.08 g/dm3/ 58.5 g/mol
Molarity = 0.1039 mol/dm3
The molarity of the solution is 0.1039 mol/dm3
Question 9 of 20
Which of the following is an example of a chemical change?
O A. A solid dissolving in a liquid
B. A solid reacting with a gas to form a new solid
C. A mixture of a solid and a liquid famming
O D. A liquid evaporating into a gas
Answer:B
Explanation:
The solid and the gas are forming a brand new solid which is a chemical change
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A solid reacts with a gas to form a new solid.
Hence, option B is correct.
What is a chemical change?A chemical change happens when one chemical substance is transformed into one or more different substances, such as when iron becomes rust. Chemical changes occur through the process of chemical reactions, and the resulting substances have different properties because their atoms and molecules are arranged differently.
A chemical change occurs when a substance's chemical identity changes. An example of this is rusting. When an iron nail comes into contact with water and air, it rusts, forming a brown-red substance. This process changes the chemical composition of the initial substance.
Hence, a solid reacts with a gas to form a new solid is a chemical change.
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Carbon dioxide gas reacts with liquid water to produce aqueous carbonic acid.” Which chemical equation correctly translates this description? CO2 (s) + H2O (g) → H2CO3 (s) CO2 (l) + H2O (l) → H2CO3 (l) CO2 (g) + H2O (g) → H2CO3 (aq) CO2 (g) + H2O (l) → H2CO3 (aq)
Answer: CO2(g)+H2O(I) > H2CO3(Aq)
Explanation:
Got it right?
) Which property listed below is NOT that associated with a metallic atomic solid: (a) electrically (b) elastic (c) high melting (d) tough insulating point
Answer:
I'd say elastic
Metallic atomic solids, forming metal objects, can pass electric currents through, need a lot of heat to melt, and since electricity can easily pass through, it's quite tough/impossible to find an insulating point.
Which products are formed when aluminum is added to a silver chlorine solution?
Answer:
Alcl3 and Cl2
Explanation:
the product above will be formed
Answer:
silver (Ag) and aluminum chloride (AlCl₃)
Explanation:
The reaction between aluminum and silver chloride is a single replacement reaction. A single replacement reaction is when one element switches places with another.
Al + 3AgCl ➔︎ 3Ag + AlCl₃
In the reaction, the cations (positively charged ions) switch places. Aluminum (Al) switches places with Silver (Ag). So, the products of the reaction are silver and aluminum chloride.
Hope this helps.
4. What are the potential sources of error that might cause disagreement between the activity series' prediction of reactions and your observations of reactions
Answer:
1. Not to have enough salt water on the foil
2.not cleaning the foil well to remove interfering materials
Just as one dozen eggs always has 12 eggs in it, one mole of a
substance always has the same number of particles in it, 6.02 x 1023.
If you measure 27.0 g of aluminum foil, which is 1 mole of aluminum,
how many Al atoms does it contain?
Answer:
[tex]6.022x10^{23}atoms \ Al[/tex]
Explanation:
Hello,
In this case, given the described concept regarding the Avogadro's number, we can easily notice that 27.0 g of aluminium foil has 6.022x10²³ atoms as shown below based on the mass-mole-particles relationship:
[tex]27.0gAl*\frac{1molAl}{27.0gAl} *\frac{6.022x10^{23}atoms \ Al}{1molAl} \\\\=6.022x10^{23}atoms \ Al[/tex]
Notice this is backed up by the fact that aluminium molar mass if 27.0 g/mol.
Best regards.
10. Which functional group is present in the molecule?
Alcohol
It carries at least one hydroxyl functional group ( i.e -OH ) bound to a saturated carbon atom.
Therefore the functional group present is -OH functional group.
Answer:
Carboxylic acid
Explanation:
4. Use the reaction: 3 NaOH + H3PO4 Na3PO4 + 3 H2O a. How many mL of 0.225 M NaOH will react with 4.568 gram H3PO4? 54 b. How many mL of 0.385 M H3PO4 react with 50.0 mL of 0.404 M NaOH? c. What is the maximum amount of Na3PO4 that is formed from the reaction of 25.00 mL of 0.1050 M NaOH and 15.00 mL of 0.08650 M H3PO4? d. What is the molarity of Na3PO4 in the solution prepared in c?
Answer:
a. 621.5 mL
b. 17.5 mL
c. 0.875 moles of salt
d. 0.022 M
Explanation:
3 moles of sodium hydroxide react to 1 mol of phosphoric acid in order to produce 1 mol of sodium phosphate and 3 moles of water. The reaction is:
3 NaOH + H₃PO₄ → Na₃PO₄ + 3H₂O
a. Ratio is 1:3. We convert the mass of the acid, to moles:
4.568 g / 97.994 g/mol = 0.0466 moles
1 mol of acid react to 3 moles of hydroxide, therefore
0.0466 moles will react to (0.0466 . 3) /1 = 0.140 moles
Molarity (M) → mmol / mL
We convert mol to mmol → 0.140 mol . 1000 mmol / 1mol = 140 mmol
mL = mmol / M → 140 mmol / 0.225M = 621.5 mL
b. Ratio is 3:1. We need to determine, the moles of base.
50 mL . 0.404 M = 20.2 mmol → 0.0202 mol of NaOH
3 moles of hydroxide react to 1 mol of acid.
20.2 mmol of hydroxide would react to (20.2 . 1) / 3 = 6.73 mmol
mL = mmol / M → 6.73 mmol / 0.385M = 17.5 mL
c. First of all, we need to find out the limiting reactant:
25 mL . 0.1050M = 2.625 mmoles of base
15mL . 0.08650M = 1.2975 mmoles of acid.
1 mol of acid need 3 moles of base, for reaction
1.2975 mmol of acid would need (1.2975 . 3) /1 = 3.8925 mmol of base
We do not have enough base, so this is the limiting. (we need 3.8925 mmoles and we only have 2.625 mmoles)
So now, we propose:
3 moles of base can produce 1 mol of salt
2.625 mmoles of base would produce (2.625 . 1) /3 = 0.875 mmoles
d. To find out molarity, we need the total volume of solution:
25 mL + 15 mL = 40 mL
0.875 mmoles of salt / 40mL of solution = 0.022 M
A buffer solution is prepared from equal volumes of 0.200 M acetic acid and 0.600 M sodium acetate. Use 1.80 x 10−5 as Ka for acetic acid. (a) What is the pH of the solution? (b) Is the solution acidic or basic? (c) What is the pH of a solution that results when 3.00 mL of 0.034 M HCl is added to 0.200 L of the original buffer
Answer:
a. pH = 5.22
b. Acidic.
c. pH = 5.14
Explanation:
a. It is possible to find the pH of a buffer using Henderson-Hasselbalch equation (H-H equation):
pH = pKa + log₁₀ [A⁻] / [HA]
Where pKa is -log Ka (For acetic acid = 4.74), [A⁻] is molar concentration of conjugate base (Acetate salt) and [HA] concentration of the weak acid (Acetic acid).
Replacing:
pH = 4.74 + log₁₀ [0.600M] / [0.200M]
You use the concentration of the acetic acid and sodium acetate because you're adding equal volumes, doing the ratio of the species the same
pH = 5.22
b. As the solution has a pH lower that 7.0, it is considered as a acidic solution.
c. When you add HCl to the buffer, the reaction is:
CH₃COO⁻ + HCl → CH₃COOH + Cl⁻
Where acetate ion reacts with the acid producing acetic acid.
As you have 0.200L of the buffer, 0.100L are of the acetate ion and 0.100L of the acetic acid. Initial moles of both compounds and moles of HCl added are:
CH₃COO⁻: 0.100L ₓ (0.600mol / L) = 0.0600 moles
CH₃COOH: 0.100L ₓ (0.200mol / L) = 0.0200 moles
HCl: 3.0mL = 3x10⁻³L ₓ (0.034mol / L) = 0.00010 moles HCl
The moles added of HCl are the same moles you're consuming of acetate ion and producing of acetic acid. Thus, moles after the reaction are:
CH₃COO⁻: 0.0600 moles - 0.0001 moles = 0.0509 moles
CH₃COOH: 0.0200 moles + 0.0001 moles = 0.0201 moles
Replacing in H-H equation:
pH = 4.74 + log₁₀ [0.0509moles] / [0.0201moles]
pH = 5.14
(a) The pH of the solution is 5.22
(b) The solution is Acidic
(c) The pH of the resultant solution is 5.14
Henderson-Hasselbalch Equation:(a) The pH of a buffer can be calculated by using (H-H equation):
pH = pKa + log₁₀ [A⁻] / [HA]
Where pKa is -log Ka (for acetic acid = 4.74),
[A⁻] is the molar concentration of Acetate salt, and
[HA] concentration of the Acetic acid
According to the question:
pH = 4.74 + log₁₀ [0.600M] / [0.200M]
pH = 5.22
(b) The pH of the solution is lower than 7.0, therefore it is an acidic solution.
(c) After adding HCl to the buffer, the reaction is:
CH₃COO⁻ + HCl → CH₃COOH + Cl⁻
We have 0.200L of the buffer, 0.100L are of the acetate ion and 0.100L of the acetic acid.
The initial amount of compounds added are:
CH₃COO⁻: 0.100L ₓ (0.600mol / L) = 0.0600 moles
CH₃COOH: 0.100L ₓ (0.200mol / L) = 0.0200 moles
HCl: 3.0mL = 3x10⁻³L ₓ (0.034mol / L) = 0.00010 moles HCl
The HCl reacts with the same amount of acetate ion and produces acetic acid. Thus, moles after the reaction are:
CH₃COO⁻: 0.0600 moles - 0.0001 moles = 0.0509 moles
CH₃COOH: 0.0200 moles + 0.0001 moles = 0.0201 moles
From the H-H equation:
pH = 4.74 + log₁₀ [0.0509moles] / [0.0201moles]
pH = 5.14
Learn more about H-H equation:
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conductors such as metal are materials that have a
Answer:
Conductors allow a flow of current or a charge of flow
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