In this question, we have a situation in which we have to use the Calorimetry formula, which is how much heat was released or absorbed (in Joules), after we had a change in temperature of a compound. The formula for this Calrimetry question is:
Q = mcΔT
Where:
Q = is energy as Heat
m = mass in grams
c = is the specific heat capacity
ΔT = the change in temperature, calculated as Final Temperature - Initial T
We have:
m = 75.0 grams
c = for water is 4.184 J/g°C
ΔT = 27.5 - 100 = -72.5°C
Now adding these values into the formula:
Q = 75 * 4.184 * (-72.5)
Q = - 22750.5 Joules, or -22.75 kJ
What is the molarity of a solution that contains 75.0 grams of KNO3 dissolved in 0.350 L of solution?Group of answer choices4.14 M solution2.12 M solution8.18 M solution1.07 m solution
Explanation:
The molarity (mol/L) is the ratio between the amount of substance in the solute (n1) and the volume of the solution in liters (V). The formula to find the molarity is: M = n1/V
First, let's transform 75.0 grams of KNO3 into moles using the following formula:
moles = mass/molar mass
molar mass of KNO3 is 101.1032 g/mol
moles = 75/101.1032
moles = 0.742 moles
So:
M = 0.742/0.350
M = 2.12 M
Answer: 2.12 M solution
what mass of KHC8H4O4 would be neutralized by 25.25 ml of 0.1034 NaOH
KHC₈H₄O₄ would be neutralized by 25.25 ml of 0.1034 NaOH then the mass of KHC₈H₄O₄ is 5.151 g
Mass is a measure of the amount of matter in a substance or an object here given data is KHC₈H₄O₄ would be neutralized by 25.25 ml of 0.1034 NaOH
Then the reaction is
KHC₈H₄O₄ (aq) + NaOH (aq) → NaKC₈H₄O₄ (aq) + H₂O
Then the concentration of NaOH is equal to the 0.1 M then we use this and the volume given above to determine the mass of KHC₈H₄O₄
0.1 mol/L NaOH (25.25 ml) ( 1 mol KHC₈H₄O₄/ 1 mol NaOH) (204 g / 1 mol) = 5.151 g KHC₈H₄O₄
5.151 g mass of KHC₈H₄O₄ would be neutralized by 25.25 ml of 0.1034 NaOH
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In the equation 2KClO3-> 2KCl+3O2 how many many miles of potassium chloride are produced alongside 0.85 moles of oxygen gas
We first verify that the reaction equation is balanced. To do this we have the atoms of each element on each side of the reaction. we have 2 potassium atoms, 2 chlorine atoms, and 6 oxygen atoms on each side of the reaction. So the equation is balanced.
Now, by stoichiometry we can find the moles of KCl. The KCl to O2 ratio is 2/3 so the moles of KCl will be:
[tex]\begin{gathered} MolKCl=givenmolO_2\times\frac{2molKCl}{3molO_2} \\ MolKCl=0.85molO_2\times\frac{2molKCl}{3molO_2}=0.57molKCl \end{gathered}[/tex]The moles of potassium chloride produced is 0.57mol KCl
A container of an ideal gas is at STP. It holds 2.90mol of gas.What is the volume of the gas?L
Explanation:
We are given: 2.90mol of ideal gas
At STP: Pressure = 1 atm
: Temperature = 273.15 K
: R = 0.08205 L.atm/mol.K
Using the ideal gas law:
[tex]\begin{gathered} PV\text{ = nRT} \\ \\ \therefore V\text{ = }\frac{nRT}{P}\text{ = }\frac{2.9\text{ }\times0.08205\times273.15}{1}\text{ = 64.99 L} \end{gathered}[/tex]Answer:
V = 64.99 L
Write the formula for the following compounds.
The cation, anion, and formula for the given compounds are as follows:
sodium iodide: Na⁺; I⁻; Nalzinc sulfide: Zn²⁺; S²⁻; ZnSmagnesium nitride: Mg²⁺; N³⁻; Mg₃N₂barium phosphide: Ba²⁺; P³⁻; Ba₃P₂calcium chloride: Ca²⁺; Cl⁻; CaCl₂aluminum fluoride: Al³⁺; F⁻; AlF₃lithium oxide: Li⁺; O²⁻; Li₂OWhat is the formula of a compound?The formula of a compound is the formula that represents the compounds using the symbols of the elements and showing the ratio in which the elements combine to form the compound.
The ratio in which they combine is written as subscripts in the formula.
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It took 13,750 Joules of energy to raise the temperature of water to 45.0 °C. If you have 125.0 grams
of water and the specific heat of water is 4.18 J/g °C, what is the starting temperature?
The initial temperature of water can be calculated from the heat energy using calorimetric equation. The initial temperature is obtained as 18.65 °C.
What is calorimetric equation?Calorimetry is an analytical tool used to determine the heat energy absorbed or released in a chemical reaction. The heat energy q, mass of the substance m and the specific heat capacity c with a temperature difference ΔT is written as follows:
q = m c ΔT.
Here, the heat energy required for raising the temparture of 125 g of waater to 45 °C is 13750 joules . Then, the initial temperature be x, then x can be calculated as follows:
13750 J = 125 g × 4.18 J/g °C × (45 - x °C)
x = 45 - [ 13750 J / (125 g × 4.18 J/g °C) ]
= 18. 65 °C.
Therefore, the initial temperature was 18. 65 °C.
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Sodium chloride, NaCL, forms when the metal sodium and the nonmetal chlorine join chemically. What type of substance is sodium chloride?A. a salt compoundB. an elementC. a heterogeneous mixtureD. a solution
Question 1
Answer & explanation
Sodium chloride is commonly known as table salt. It is an ionic compound with the chemical formula NaCl.
NaCl is a compound
Question 2
Answer & explanation
It is possible to separate a solution by physical means.
A compound Y gave the following result on elemental analysis. C (85.7%), and H (14.3%) given that the relative molecular mass of Y is 42, calculate the molecular formula. Write the possible structure.
C3H6 is the molecular formula.
moles of C present in compound =36/12=3 moles.
moles of H present in compound =6/1=6 moles.
The mole concept is a helpful technique to quantify the amount of a material. When dealing with particles at the atomic (or molecular) level, it is recognized that even one gram of a pure element has a vast number of atoms. The mole concept is widely used in this context. The most used unit of measurement is the "mole," which is a count of a significant number of particles.
The number 6.02214076*1023, also known as the Avogadro constant, is usually denoted by the letter "NA". Among the elementary things that may be represented in moles are atoms, molecules, monoatomic and polyatomic ions, as well as other particles (such as electrons)
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Understanding resonance is a key concept to understanding the different ways a molecule can exist, simultaneously. How many resonance structures does the following molecule have: NO2
1) We have to write the Lewis structure of the molecule.
I don’t understand how to solve this and I don’t get ionic equation
Explanation:
Spectator ions refers to elements/molecules that do not form part of the reaction. Basically, these elements/molecules are in the same state in the reactant and product side. From the given reaction, Ca and SO4 change their state from aqueous to solid and Na and Cl do not change their state. Therefore, Na and Cl are spectator ions and Ca and SO4 are not spectator ions.
Answer:
The correct option is C.
When bond strength increase .number of hydrogen decrease .Why
Answer:
As bond strength increases, the atoms in the bond are pulled more tightly together.
Explanation:
As the bond energy increases the bond length decreases
GOOD LUCK!
Carrie is trying to figure out the number of calories in a cube of cheese. To do this, she pours 154.7 mL of water into an aluminum can suspended from a ring stand. She takes the temperature of the water, and finds it to be 16.3 degrees Celsius. Then, she places the 5.23 gram cube of cheese under the can and lights it on fire! While the cheese is burning and for a few minutes after it is done, Carrie records the temperature of the water, finding that it levels out at 24.1 degrees Celsius. How many calories of heat were gained by the water? Please answer to the nearest 0.1 calorie.
To calculate the calories that the water gained, we must use the specific heat of the water. The specific heat of water is 1cal/g°C, which means that it takes one calorie to raise one gram of water 1°C.
Now, we need the mass of water and the temperature difference.
We will calculate the mass of water from its density, the density of water is 1mL/g. Density is defined as:
[tex]Density=\frac{Mass}{Volume}[/tex]We clear the mass and replace the known data:
[tex]Mass=1g/ml\times154.7mL=154.7g[/tex]Now, the temperature difference will be:
[tex]\begin{gathered} \Delta T=T_2-T_1 \\ \Delta T=24.1\degree C-16.3\degree C=7.8\degree C \end{gathered}[/tex]Calories gained by water are calculated from the following equation:
[tex]Q=mCp\Delta T[/tex]where,
Q is the heat or energy that the substance absorbs or releases. In this case, the water will absorb energy.
m is the mass of water = 154.7g
Cp is the specific heat of water, 1cal/g°C
dT is the difference of temperature, 7.8°C
Now, we replace the known data:
[tex]\begin{gathered} Q=154.7g\times1\frac{cal}{g.\degree C}\times7.8\degree C \\ Q=1206.7cal \end{gathered}[/tex]Answer: The water gained 1206.7 calories of heat
How many moles are in 127.49 grams of Ec2H406?Ec has a molar mass of 31.79 grams/mole.(Hint: You need to determine the molar mass of Ec2H406 to solve this problem).
As the hint says the first thing we have to do is to determine the molar mass of our compound. To do so we need the molar mass of one atom of each element present in our compound.
molar mass of Ec = 31.79 g/mol
molar mass of H = 1.01 g/mol
molar mass of O = 16.00 g/mol
Since one molecule of Ec₂H₄0₆ has 2 atoms of Ec, 4 atoms of H and 6 atoms of O, we can find the molar mass of Ec₂H₄0₆ like this:
molar mass of Ec₂H₄0₆ = 2 * molar mass of Ec + 4 * molar mass of H + 6 * molar mass of O
molar mass of Ec₂H₄0₆ = 2 * 31.79 g/mol + 4 * 1.01 g/mol + 6 * 16.00 g/mol
molar mass of Ec₂H₄0₆ = 163.62 g/mol
Now we can find the number of moles that we have in 127.49 g of Ec₂H₄0₆.
number of moles = mass of sample/molar mass
number of moles = 127.49 g / (163.62 g/mol)
number of moles = 0.7792 moles
Answer: Therea are 0.7792 moles in 127.49 g of our compound.
What is the energy of a photon of light that has a frequency of 7.87 × 10^15 Hz?
The question requires us to calculate the energy of a photon given that its frequency is 7.87 × 10^15 Hz.
To calculate the energy of a photon, we can use the following equation:
[tex]E=h\times f[/tex]where h is the Planck's constant (6.626 x 10^-34 Jxs) and f is the frequency (in Hz or 1/s). (Note that the unit Hz is equivalent to s^-1)
Then, applying the frequency provided and the Planck's constant to the equation, we have:
[tex]E=(6.626\times10^{-34}J\mathrm{}s)\times(7.87\times10^{15}s^{-1})=5.21\times10^{-18}J[/tex]Therefore, the energy of the photon is 5.21 x 10^-18 J.
The first and second ionization energies of K are 419 kJ/mol and 3052 kJ/mol, and those of Ca are
590 kJ/mol and 1145 kJ/mol, respectively. Compare their values and comment on the differences.
Explanation:
Already it can be noted that both the first and second ionization energy of Ca is greater than that of K. In order to fully understand why this is, we must first look at both elements and their electron configuration.
Ionization energy is basically the energy required to remove the outermost electron in an atom
There are 3 factors that affect the ionization energy:
the size of positive nuclear chargedistance of the outermost electron from the nucleusscreening/shielding effect from inner shellsFrom the attachment of the atomic radii trend in the periodic table, we know that atomic radius decreases moving across a period i.e meaning that the outermost shell is closer to the nucleus. And we know that atomic radius increases down a group.
And in the case of K and Ca, we note that Ca has a smaller atomic radii than K, this is because an extra proton and electron is added to the atom that differs it from the previous member, K. Moving from K to Ca, we see that the electron was added to the same shell and there is another proton in the nucleus therefore the attraction of the outermost shell to the nucleus as with the size of the positive nuclear charge increased whilst the shielding effect remained the same for K and Ca, this makes it more difficult now to remove the outer most electron of Ca hence the increased ionization energy as compared to K.
The answer I understood to be correct is not correct, please see attached photo
• For a face centered cubic (fcc) unit cell , the radius r and edge length/lattice constant (a) is given by :
4r = √2 a ; given that radius = 164pm
∴ 4 * 164pm =√2 a
∴ a = (4*164pm) /√2
= 463.86 pm
≈464 pm
• The lattice constant (a) of a crystal M = 464pm
Place these in order from smallest to largest.
Ca, Fe, Ni, or Br
Order from smallest to largest are :
Br < Ni < Fe < Ca
The atomic radius is the distance between centre of nucleus of atom to the outermost shell. The trend of atomic radius in the periodic table is it increases from top to bottom as no. of shells increases. Atomic radius from left to right in the periodic table is decreases because the number of electrons increases but number of shells remain same . The valence electron are in the same outermost shell. This leads to the increase in attractive forces and this reduces the atomic radius.
Thus, Order from smallest to largest are :
Br < Ni < Fe < Ca
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To correctly balance the half reaction, what would you need to add?
1) Balance the chemical equation.
[tex]Se\rightarrow Se^{2-}[/tex]In order to balance the equation, we can add two electrons to the reactants.
So, the balance equation is
[tex]2e^-+Se\rightarrow Se^{2-}[/tex]****100 POINTS**** *WILL MARK BRAINLIEST* !!PLEASE HELP ASAP!! A manufacturer of building materials is designing a new product to be used as structural support for houses being built in the southwestern U.S. desert. Describe two macroscopic properties that should be considered by the manufacturer when designing the product.
Perhaps you like the appearance of rocks and boulders but prefer a material that stays cool in the desert heat. In this case, concrete or travertine should be your top picks. These materials have a high thermal mass and absorb the coolness of the earth below rather than the hot sun overhead
Sometimes you like how rocks and boulders look, but you'd rather have something that keeps cool in the hot desert. In this circumstance, limestone or concrete ought to be your top choices.
What is desert ?Deserts are incredibly arid places where well-adapted flora and animals can be found. Deserts may be divided into four basic categories are hot and dry, semi-arid, coastal, and cold.
The majority of specialists concur that a desert is any region of land with annual precipitation totals of less than 25 cm (10 inches). In a desert, evaporation frequently much outweighs yearly precipitation. Water is scarce for plants and other living things in all deserts.
Thus, Due to their large thermal mass, these materials absorb the cooling of the earth below rather than the heat from the sun above. Something that keeps cool in the hot desert.
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Write the basic equilibrium equation for NH₃
The question requires us to write the chemical reaction equation that represents the basic equilibrium for ammonia (NH3).
A general basic equilibrium equation can be written as:
[tex]B_{(aq)}+H_2O_{(l)}\to HB^{+_{}}_{(aq)}+OH^-_{(aq)}[/tex]where the substance B "accpets" a H+ ion and the reaction produces OH- ions as product.
Considering the information above, we can write the following basic equation for NH3:
[tex]NH_3_{(aq)}+H_2O_{(l)}\to NH_4^{+_{}}_{(aq)}+OH^-_{(aq)}[/tex]where ammonia receives an H+ ion, forming NH4+ ion and OH- ions.
10) In a solution of NiCl2, the Cl- concentration is 0.059 M. How many grams of NiCl2 are in 462 mL of this solution?
Answer
5.299 grams
Explanation
Given:
Concentration of Cl⁻ = 0.059 M
Volume of solution = 462 mL = 0.462 L
What to find:
The grams of NiCl₂ in 462 mL solution
Step-by-step solution:
The first step to write a balanced equation for the dissolution of NiCl₂:
[tex]\text{NiCl}_{2(s)}\rightarrow Ni^{2+}+2Cl^-[/tex]From the balanced equation; 1 mole of NiCl₂ produces 2 moles of Cl⁻
Given that the concentration of Cl⁻ = 0.059 M, so the concentration of Ni⁺ will be:
[tex]\frac{\lbrack Cl^-\rbrack}{2}=\frac{0.059}{2}=0.0295\text{ }M\text{ }Ni^{2+}[/tex]So that Molarity, M, of NiCl₂ = 0.059 M + 0.0295 = 0.0885 M
[tex]Number\text{ of moles NiCl}_2=Molarity\times Vol\text{ume in L}[/tex]Number of moles of NiCl₂ = 0.0885 M x 0.462 L = 0.040887 mol
The last step is to convert the number of moles of NiCl₂ to grams using the formula below:
[tex]\text{Number of moles }=\frac{Mass}{Molar\text{ mass}}[/tex]From the Periodic Table;
Molar mass of NiCl₂ = 129.5994 g/mol
So, mass of NiCl₂ in 462 mL solution = 0.040887 mol x 129.5994 g/mol = 5.299 grams
The definition of a limiting reactant can be summarized as:
Answer:
Explanation:
Here, we want to get the correct answer choice
The limiting reactant is the reactant that gets used up and that dictates the amount of products we can have
Take for example, we want to build a car, and we have 5 steering wheels but 100 tyres
A car needs 1 steering wheel and 4 tyres. Thus, the number of steering wheels will determine the number of possible cars produced
The steering wheel is thus the limiting reactant
The correct answer choice is that the reactant that is usede up is the limiting reactant
Calculate the pOH of the following solutions [OH-] = 4.3 x 10-6 M[OH-] = 2.0 x 10-6 M[OH-] = 4.5 x 10-11
Step 1 - Understanding the definition of pOH
pOH is defined as:
[tex]pOH=-log[OH^-\rbrack[/tex]I.e., we can calculate the pOH by knowing the concentration of OH- in the solution.
Step 2 - Calculating the pOH of the given solutions
a) The first solution has a OH- concentration of 4.3 x 10-6 M. We just need to set this value in the definition of pOH:
[tex]\begin{gathered} pOH=-log4.3\times10^{-6}=-[log4.3+(-6)log10\rbrack \\ \\ pOH=-log4.3+6=6-0.63=5.37 \end{gathered}[/tex]b) The second solution has a OH- concentration of 2.0 x 10-6 M. Let's calculate its pOH:
[tex]\begin{gathered} pOH=-log2\times10^{-6}=-[log2+(-6)log10\rbrack \\ pOH=-log2+6=6-0.3=5.69 \end{gathered}[/tex]c) The third solution has a OH- concentration of 4.5 x 10-11 M. Let's calculate its pOH:
[tex]\begin{gathered} pOH=-log4.5\times10^{-11}=-[log4.5+(-11)log10\rbrack \\ pOH=-log4.5+11=11-0.65=10.35 \end{gathered}[/tex]Answer: the pOH of the solutions are, respectively, 5.37, 5.69 and 10.35
Question 12 Ti + 3 Ca(OH)22 Ti(OH)3 + 3 CaIf 125 grams of calcium hydroxide is reacted, how much calcium metal will be produced?134 grams67.6 grams22.5 grams203 grams
67.57g of calcium metal will be produced.
1st) We need the balanced reaction and the molar mass of calcium hydroxide and calcium metal:
[tex]2Ti+3Ca(OH)_2\text{ }\rightarrow2Ti(OH)_3\text{ + 3 Ca}[/tex]- Ca molar mass: 40 g/mol
- Ca(OH)2 molar mass: 74 g/mol
According to the balanced reaction, we know that 3 moles of calcium hydroxide produces 3 moles of calcium metal.
With the molar mass of the compounds we can convert moles to grams, so we can see that 222g of calcium hydroxide (3 x 74g) can produce 120g of calcium metal (3 x 40g).
2nd) Now we can calculate the amount of calcium metal that will be produced from 125 grams of calcium hydroxide, with a mathematical Rule of Three:
[tex]\begin{gathered} 222gCa(OH)_2-120gCa \\ 125gCa(OH)_2-x=\frac{125g\cdot120g}{222g} \\ x=67.57gCa \end{gathered}[/tex]Finally, 67.57g of calcium metal will be produced from 125g of calcium hydroxide.
H2O(I)+40.7 KJ > H2O(g)endothermic or exothermic
ANSWER
Endothermic reaction
EXPLANATION
Given that;
[tex]\text{ H}_2O_{(l)}\text{ + 40.7KJ }\rightarrow\text{ H}_2O_{(g)}[/tex]In the reaction above, there is a transition from liquid water to steam. This phase change is called boiling.
During the process, heat is absorbed from the surroundings.
Therefore, the reaction is an endothermic reaction.
What is the volume of the gas when the temperature is 400 K?
10 L is the volume of the gas when the temperature is 400 K.
V/T = constant
T1 = 400 K ,
V1 = 20 L
T2 = 200 K
V2 = ?
V1 / T1 = V2 / T2
20 / 400 = V2 / 200
V2 = 10 L
The area contained within an object's limits determines its volume in three dimensions. On occasion, it is referred to as the object's capacity. The volume of an object can be used to calculate how much is needed to fill it; for instance, how much water is needed to fill a bottle, aquarium, or water tank.
A sphere is the most basic and prevalent type of three-dimensional shape. Spheres are commonly observed in the form of balls, globes, ornamental lights, oranges, etc.
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HCl +H2O -> H3O^+ + Cl^-In the reaction shown above, theis the Bronsted-Lowry base, and theis the Bronsted-Lowry acid.A)Cl;HB)H;ClC)H2O;HClD)HCl;H2O
H₂O is the Bronsted-Lowry base and HCl is the Bronsted-Lowry acid. Option C is correct.
Explanations:Bronsted-Lowry acid is defined as the ion or molecule that donates a hydrogen ion (H⁺) in a chemical reaction. Since H⁺ is a proton, hence a Bronsted - Lowry acid is a proton donor meaning that we can determine the Bronsted - Lowry acid in a chemical reaction by simply looking out for the molecule that loses a hydrogen ion (proton).
From the chemical reaction given
[tex]HCl+H_2O\to H_3O^++Cl^-[/tex]We can see that hydrochloric acid (HCl) donates a proton to have one less proton on the product side than on the reactant. Therefore, HCl in this case will be the Bronsted-Lowry acid since it acts as the donor.
Similarly, a Brønsted-Lowry base is a molecule or ion that accepts hydrogen ions in a reaction. From the reaction, you can see that water (H₂O) is the molecule that accepts this hydrogen ion to form a hydronium ion (H₃O⁺). Hence, the water molecule will act as a Bronsted - Lowry base
Rigor mortis occurs because ________.
A) the cells are dead
B) sodium ions leak out of the muscle
C) no ATP is available to release attached actin and myosin molecules
D) proteins are beginning to break down, thus preventing a flow of calcium ions
Answer:
C) no ATP is available to release attached actin and myosin molecules
Explanation:
Rigor mortis occurs because no ATP is available to release attached actin and myosin molecules. Therefore, the correct option is option C.
What is Rigor mortis?The fourth stage of death is known as rigour mortis, or postmortem rigidity. One of the telltale indications of death is the stiffening of the corpse's limbs as a result of postmortem chemical changes inside the muscles. Rigor mortis can develop in humans as quickly as eight hours after death. Rigor mortis does not constitute a lifelong condition, despite popular belief and mythology, and it starts to subside within hours of commencement.
It typically only lasts 8 hours at "room temperature." Following death, an organism's aerobic respiration stops, reducing the supply of oxygen needed to produce adenosine triphosphate (ATP). When a muscle relaxes, ATP is necessary to cause the actin-myosin cross-bridges to separate. Rigor mortis occurs because no ATP is available to release attached actin and myosin molecules.
Therefore, the correct option is option C.
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In the hydrate formula CuSO4 x H2O, how many waters were there?
Given that the formual shows coefficients of 1, we can deduct that there's 1 mole of water in the hydrate formula.
Therefore, there's one mole of water.
NaOH(s) was added to 1.0 L of HClO4(aq) 0.43 M. Calculate [H3O+] in the solution after the addition of 0.10 mol of NaOH(s).Calculate [H3O+] in the solution after the addition of 0.81 mol of NaOH(s).
Answer:
a) 0.33 M
b) 2.63x10^-14 M
Explanation:
1st) It is necessary to write and balance the chemical reaction:
[tex]HClO_4+NaOH\rightarrow NaClO_4+H_2O[/tex]From the balanced reaction we can see that 1 mole of HClO4 reacts with 1 mole of NaOH.
2nd) Since the relation between the acid (HClO4) and the base (NaOH) is 1:1, the 0.10 moles of NaOH will react with 0.10 moles of acid:
[tex]\begin{gathered} RemainingSolution=0.43moles\text{ - }0.10moles \\ RemainingSolution=0.33moles \end{gathered}[/tex]So, in the solution 0.33 moles of HClO4 will remain unreacted, and the concentration of H3O+ will be 0.33M.
3rd) In this case we can proceed the same as in the first part:
[tex]\begin{gathered} RemainingSolution=0.43moles-0.81moles\text{ } \\ RemainingSolution=-0.38moles \end{gathered}[/tex]In this case, the addition of 0.81 moles of NaOH neutralizes all the acid in the solution and 0.38 moles of the base will remain unreacted.
So, the concentration of OH- will be 0.38M, and it is necessary to calculate the pOH of the solution, because when OH- is left over, the solution will be basic:
[tex]\begin{gathered} pOH=-log\lbrack OH^-\rbrack \\ pOH=-log(0.38) \\ pOH=0.42 \end{gathered}[/tex]The pOH of the solution is 0.42.
4th) Now with the pOH we can calculate the pH of the solution, with the following formula:
[tex]\begin{gathered} pH+pOH=14 \\ pH+0.42=14 \\ pH=14-0.42 \\ pH=13.58 \end{gathered}[/tex]The pH of the solution is 13.58.
5th) Finally, with the value of pH and the pH formula, we can calculate [H3O+]:
[tex]\begin{gathered} pH=-log\lbrack H3O^+\rbrack \\ 13.58=-log\lbrack H3O^+\rbrack \\ -13.58=log\lbrack H3O^+\rbrack \\ 10^{(-13.58)}=\lbrack H3O^+\rbrack \\ 2.63*10^{-14}M=\lbrack H3O^+\rbrack \end{gathered}[/tex]So, the concentration of H3O+ is 2.63x10^-14M.