Answer:
1. 4.93 = pKb of the weak base
2. pH = 12.61
Explanation:
1. When a weak base, B, is being titrated with HCl, the reaction occurs as follows:
B + HCl → BH⁺ + Cl⁻
That means the moles added of HCl are the moles of BH⁺ produced and moles of B are initial moles of B - Moles of HCl
Thus:
Moles B:
Initial moles:
0.0250L * (0.130mol / L) = 3.25x10⁻³ moles B
Moles HCl:
8.5x10⁻³L * (0.130mol / L) = 1.105x10⁻³ moles HCl
3.25x10⁻³ - 1.105x10⁻³ =
2.145x10⁻³ moles BMoles BH⁺ = Moles HCl:
1.105x10⁻³ moles BH⁺pH of the buffer made from B/BH⁺ is determined using H-H equation for weak bases:
pOH = pKb + log [BH⁺] / [B]
Where pOH is 14-pH = 14-9.36 = 4.64
pKb is pKb of the weak base, our unknown.
[BH⁺] could be taken as moles of BH⁺ = 1.105x10⁻³ moles
And [B] as moles of B = 2.145x10⁻³ moles B
Replacing:
pOH = pKb + log [BH⁺] / [B]
4.64 = pKb + log [1.105x10⁻³ moles] / [2.145x10⁻³ moles]
4.64 = pKb -0.288
4.93 = pKb of the weak base2. When HCl and NaOH are in solution the reaction that occurs is:
HCl + NaOH → H₂O + NaCl
To find pH we need to determine, first, which reactant is in excess:
Moles HCl:
0.023L * (0.230mol / L) = 5.29x10⁻³ moles
Moles NaOH:
0.033L * (0.0230mol / L) = 7.59x10⁻³ moles
That means NaOH is in excess and after the reaction will remain:
7.59x10⁻³ moles - 5.29x10⁻³moles = 2.3x10⁻³ moles NaOH = Moles of OH⁻
In 23+33mL = 56mL = 0.056L:
2.3x10⁻³ moles OH⁻ / 0.056L = 0.0411M [OH-]
As pOH = -log [OH-]
pOH = 1.39
pH = 14 - pOH
pH = 12.61For a 0.300 mol sample of helium gas in a 0.200 L container at 248K, will the pressure be greater if calculated with the ideal gas law or the van der Waals equation, and by roughly how much? (For He,a=0.0342L2atmmol2,b=0.0237 Lmol)
Answer:
It changes by roughly 1 atm.
Explanation:
Hello!
In this case, since the ideal gas equation differs from the van der Waals' one by the presence of the a and b parameters which correct the assumption of no interactions into the container, they are written as:
[tex]P=\frac{nRT}{V}\\\\P=\frac{RT}{v_m-b}-\frac{a}{v_m^2}[/tex]
Thus, the pressure via the ideal gas equation is:
[tex]P=\frac{0.300mol*0.082\frac{atm*L}{mol*K}*248K}{0.200L}=30.5atm[/tex]
And the pressure via the van der Waals equation, considering the molar volume (vm=0.200L/0.300L=0.667L/mol) is:
[tex]P=\frac{0.082\frac{atm*L}{mol*K}*248K}{0.667L/mol-0.0237L/mol}-\frac{0.0342atm*L^2/mol^2}{(0.667L/mol)^2}\\\\P=31.6atm-0.0769atm\\\\P=31.5atm[/tex]
It means that the pressure change by 1 atm, which is not a significant difference for helium.
The difference in pressure calculated by the two methods is 84 atm.
The ideal gas equation is given by
PV =nRT
From the data given in the question;
P = ?
V = 0.200 L
n = 0.300 mol
T = 248K
R = 0.082 atmLK-1Mol-1
P = nRT/V
P = 0.300 mol × 0.082 atmLK-1Mol-1 × 248K/0.200 L
P = 30.5 atm
From Van der Waals equation;
P = RT/V - b - a/V^2
P = (0.082 × 248/0.200 - 0.0237) - (0.0342/ 0.200^2)
P = 114.5 atm
The difference in pressure calculated by the two methods is;
114.5 atm - 30.5 atm = 84 atm
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A buffer solution is made that is 0.347 M in H2C2O4 and 0.347 M KHC2O4.
1. If Ka for H2C2O4 is 5.90E^-2, what is the pH of the buffer solution?
b. Write the net ionic equation for the reaction that occurs when 0.070 mol KOH is added to 1.00 L of the buffer solution.
Answer:
1. pH = 1.23.
2. [tex]H_2C_2O_4(aq) +OH^-(aq)\rightarrow HC_2O_4^-(aq)+H_2O(l)[/tex]
Explanation:
Hello!
1. In this case, for the ionization of H2C2O4, we can write:
[tex]H_2C_2O_4\rightleftharpoons HC_2O_4^-+H^+[/tex]
It means, that if it is forming a buffer solution with its conjugate base in the form of KHC2O4, we can compute the pH based on the Henderson-Hasselbach equation:
[tex]pH=pKa+log(\frac{[base]}{[acid]} )[/tex]
Whereas the pKa is:
[tex]pKa=-log(Ka)=-log(5.90x10^{-2})=1.23[/tex]
The concentration of the base is 0.347 M and the concentration of the acid is 0.347 M as well, as seen on the statement; thus, the pH is:
[tex]pH=1.23+log(\frac{0.347M}{0.347M} )\\\\pH=1.23+0\\\\pH=1.23[/tex]
2. Now, since the addition of KOH directly consumes 0.070 moles of acid, we can compute the remaining moles as follows:
[tex]n_{acid}=0.347mol/L*1.00L=0.347mol\\\\n_{acid}^{remaining}=0.347mol-0.070mol=0.277mol[/tex]
It means that the acid remains in excess yet more base is yielded due to the effect of the OH ions provided by the KOH; therefore, the undergone chemical reaction is:
[tex]H_2C_2O_4(aq) +OH^-(aq)\rightarrow HC_2O_4^-(aq)+H_2O(l)[/tex]
Which is also shown in net ionic notation.
Best regards!
Is iron man made or natural
Answer:
Iron is natural. Paper is man-made
Explanation:
Answer:
iron
Explanation:
i am a metal with electrons in 5 energy levels that can form ions with a +2 charge
I need help, due in 30 mins
Answer:
1.Reaction rate is how fast a chemical reaction proceeds.
2.Nature of the reaction, Pressure factor
, Solvent, Catalyst and inhibitors.
3.Physical change is a temporary change. A chemical change is a permanent change. A Physical change affects only physical properties i.e. shape, size, etc.
4. One example of the effect of temperature is the use of lightsticks or glowsticks.
5.When the particle size of a fixed mass of a solid reactant becomes smaller, the total exposed surface area becomes larger, the rate of reaction increases. an example could be ice and water when the atoms are stuck together a solid but all over the place as a liquid.
6. Sometimes a reaction depends on catalysts to do their job. In that case, changing the concentration of the catalyst can speed up or slow down the reaction. For example, enzymes speed up biological reactions, and their concentration affects the rate of reaction.
7.A catalyst is a chemical substance that affects the rate of a chemical reaction by altering the activation energy required for the reaction to proceed. For example, a catalyst could cause a reaction between reactants to happen at a faster rate or at a lower temperature than would be possible without the catalyst.
Explanation:
I hope this helps have a great day! :)
Consider a monoprotic weak acid ( HAHA ) that is titrated with a strong base. What is the relationship between the strength of the weak acid and the pH of the solution at the equivalence point?A. There is no relationship between the strength of the acid and the pH at the equivalence point. B. The pH at the equivalence point is always 7 in an acid base titration. C. The weaker the acid, the higher the pH at the equivalence point. D. The stronger the acid, the higher the pH at the equivalence point.
Answer:
C. The weaker the acid, the higher the pH at the equivalence point.
Explanation:
In a titration, a solution which concentration is known is added gradually to another solution of unknown concentration, until the chemical reaction between the two solutions is complete.
The pH in the equivalence point is equal to 7.00 only if both the acid and base are strong. When one or both reactants are weak, the pH in the equivalence point is not equal to 7.00.
In the equivalence point, the amount of strong base (like NaOH) added is just enough to react stoichiometrically with the weak acid. The resulting solution "only" contains the conjugated base A⁻. A solution of Na⁺A⁻ is the solution of a weak base:
A⁻ + H₂O ⇄ HA + OH⁻ Kb=Kw/Ka
In the equivalence point of the titration of a weak base with a strong base, the pH is higher than 7.00 because at this point the acid is transformed into its conjugate base.
The sample of 15.0 g of KCl is dissolved into a solution with a total volume of 250.0 mL. What is the molarity of KCl in the solution?
Answer:
0.805 M.
Explanation:
Hello!
In this case, since the molarity of a solution is computing by dividing the moles of solute over the volume of solution in liters (M=n/V), for 15.0 g of potassium chloride (74.55 g/mol) we compute the corresponding moles:
[tex]n=15.0gKCl*\frac{1molKCl}{74.55gKCl}=0.201molKCl[/tex]
Next, since the volume is 0.2500 in liters, the molarity turns out:
[tex]M=\frac{0.201mol}{0.2500L} \\\\M=0.805M[/tex]
Best regards!
Electric charges that are different attract each other.
True
False
Answer:
it is true bc i looked it up
Sealed containers of fizzy drinks contain dissolved carbon dioxide. The dissolved CO2 is in equilibrium with a small quantity of gaseous CO2 at the top of the container.
Find partial pressure of CO2 gas in 355 ml can of fizzy drink at 25C if the concentration of CO2 in the fizzy drink 0.1 M. Given that Henry’s law constant for CO2 is 3.3 x 10-2 M atm-1.
What mass of CO2 is dissolved in a 355 ml can of fizzy drink when it is stored at 25C.
Answer:
3 atm
1.6 g
Explanation:
Step 1: Given data
Volume of the solution (V): 355 mLConcentration of the solution (C): 0.1 MHenry’s law constant for CO₂ (k): 3.3 × 10⁻² M atm⁻¹.Step 2: Find partial pressure (P) of CO₂ gas
We will use Henry's law.
C = k × P
P = C / k
P = 0.1 M / 3.3 × 10⁻² M atm⁻¹
P = 3 atm
Step 3: Calculate the mass of CO₂ gas
The molar mass of carbon dioxide is 44.01 g/mol.
0.355 L × 0.1 mol/L × 44.01 g/mol = 1.6 g
how could you tell what element it is if only a model was present?
What is the atomic mass of aluminum?
Help ASAP!!!! Already got a D in that class subject is science but that’s the closed I can get
Answer:
26.982
Explanation:
Use the periodic table
Help ASAP
Please and thank you
Answer: C
Explanation: Everything else is true.
How many micrograms of sodium chloride (to 2 decimal places) can be added to 527 mL of 0.00150 M silver nitrate before a precipitate forms? (Ksp = 1.80 x 10-10)
Answer:
use google
Explanation:
An Sulfur tetrafluoride gas is collected at 23.0 °C in an evacuated flask with a measured volume of 20.0 L. When all the gas has been collected, the pressure in the flask is measured to be 0.230 atm . Calculate the mass and number of moles of sulfur tetrafluoride gas that were collected. Be sure your answer has the correct number of significant digits. mass: 1 g N10 mole: mol X & ? Explanation Check
mass = 20.48 g
moles=0.1895
Further explanationIn general, the gas equation can be written
Pv=nRTwhere
P = pressure, atm
V = volume, liter
n = number of moles
R = gas constant = 0.08205 L.atm / mol K
T = temperature, Kelvin
P=0.23 atm
V=20 L
T=23+273=296 K
[tex]\tt n=\dfrac{PV}{RT}=\dfrac{0.23\times 20}{0.082\times 296}=0.1895[/tex]
mass SF₄ (MW=108,07 g/mol) :
[tex]\tt 0.1895\times 108,07 g/mol=20.48~g[/tex]
describe, in terms of the motion of particles in an object, how heat conduction transfers energy between objects or from one part of an object to another part at a lower temperature.
Answer:
Molecular movement
Explanation:
When an object gets hotter, its molecules gain more kinetic energy and then move faster. Therefore, the fast-moving molecules will cause those around them to move faster as well, and the colder (or more slow-moving molecule object) object or part is heated up.
PLS GIVE BRAINLIEST
What elements make up water?
Answer:
1 oxygen and 2 hydrogen
Look at the picture below. Name the isotope.
Answer:
carbon-13
Explanation:
Helium is a....
a. metalloid
b. nonmetal
c. metal
Answer:
NonmetalExplanation:
Assume that the top of your head has a surface area of 25 cm x 25 cm. How many newtons of force push on your head at sea level? If you estimate this area to be 100 in2, what is the force in pounds?
Answer:
(a) 6332.812 N (b) 1469.59 pounds.
Explanation:
Given that,
The surface area of the top of yu head is 25 cm x 25 cm
Area = 625 cm² = 0.0625 m²
Atmospheric pressure on it is 101325 Pa.
(a) Pressure acting on an object is given by force acting per unit area. It can be written as :
[tex]P=\dfrac{F}{A}\\\\F=PA\\\\F=101325\ Pa\times 0.0625\ m^2\\\\F=6332.812\ N[/tex]
6332.812 N of force is acting on your head at sea level.
(b) If area, A = 100 in²
We know that,
1 atm = 14.6959 pounds/in²
[tex]P=\dfrac{F}{A}\\\\F=PA\\\\F=14.6959 \ \text{Pounds}/in^2\times 100\ in^2\\\\F=1469.59\ \text{pounds}[/tex]
So, the force is 1469.59 pounds.
A. The force required to push your head at sea level is 6332.8125 N
B. The force in pound is 1469.59 lb
A. Determination of the force required at sea level.
Pressure (P) = 101325 Nm²
Area (A) = 25 cm × 25 cm = 0.25 m × 0.25 m = 0.0625 m²
Force (F) =?P = F / A
Cross multiply
F = PA
F = 101325 × 0.0625
F = 6332.8125 NTherefore, the force required to push your head at sea level is 6332.8125 N
B. Determination of the force in pounds
Area (A) = 100 in²
Pressure (P) = 14.6959 pound / in²
Force (F) =?F = PA
F = 14.6959 × 100
F = 1469.59 lbLearn more: https://brainly.com/question/13182194
give an example of coupling reaction
Answer:
An example is the formation of ATP, which is an endergonic process and is coupled to the dissipation of a proton gradient.
Explanation:
Hope this helped!
Calculate the amount of heat (in J) needed to raise the temperature of 3.50 g of water from 22.4oC to 98.8oC.
Answer:
76.4oC or 169.52oF
Explanation:
That's the amount of heat needed
The heat capacity is the heat amount lost or gained by the object in a thermodynamic system. The heat needed to raise the temperature of the water is 1117.7 Joules.
What is heat capacity?Heat capacity (q) is the heat an object loses or gains to alter the temperature of the thermodynamic system by a difference of a degree Celsius. The heat capacity is given by the mass, specific heat capacity, and temperature change.
Given,
Mass of water (m) = 3.50 gm
Specific heat (c) = 4.18 J/ g°C
The temperature change (∆T) = T₂ - T₁
= 98.8 °C - 22.4 °C
= 76.4 °C
The heat capacity is given as,
q = mc∆T
Substituting values above:
q = 3.50 gm × 4.18 J/ g °C × 76.4 °C
q = 1117.7 J
Therefore, 3.50 g of water has a heat capacity of 1117.7 Joules.
Learn more about heat capacity here:
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a sample of lead had a mass of 150 g. The molar mass of lead is 207.19 g. How many moles of lead does the sample contain?
Answer:
Explanation:
no of moles=given mass/molar mass
no of moles=150 g/207.19
no of moles=0.72
We will use dimensional analysis to answer this question.
[tex]150 g * \frac{1 g}{207.19 mol} = 0.724 mol[/tex]
The answer is 0.724 mol.
When water boils, it pushes upward against the air pressure pushing down on it. If there is less air pressure, how does that affect the pooling point ?
Please i really need help it's due today
Answer:
there is your answer hope it helped :3
What is the temperature 0 Kelvin called?
What happens at that temperature?
Answer:
0 Kelvin is called Absolute Zero. Particles will stop moving, and lose all energy.
Describe the relationship between predator and prey in a balanced ecosystem
Answer:
The predator-prey relationship helps to hold the populations of the two species in equilibrium. ... If the population of prey increases, there is more food for predators. So after a slight period, the predator population is also increasing. If the number of predators increases, more prey is captured.
Explanation:
Answer:
i eat you, you die
Explanation:
thats how life works
The reaction between iron(II) oxide and carbon monoxide produces iron and carbon dioxide. How many moles of iron can be obtained when 1.50 mol FeO reacts with an excess of CO ?
FeO+CO⟶Fe+CO2
Answer:
1.5 moles of Fe produced.
Explanation:
Given data:
Moles of FeO react = 1.50 mol
Moles of iron produced = ?
Solution:
Chemical equation:
FeO + CO → Fe + CO₂
Now we will compare the moles of ironoxide with iron.
FeO : Fe
1 : 1
1.5 : 1.5
Thus from 1.5 moles of FeO 1.5 moles of Fe are produced.
1.5 moles of Fe can be obtained when 1.50 mol of FeO reacts with an excess
of CO
Moles of FeO reacted = 1.50 mol
Moles of iron produced = ? mol
The chemical equation is given as
FeO + CO → Fe + CO₂
Comparisons of FeO and Fe show they are in the ratio 1 : 1
FeO : Fe
1.5 : 1.5
which translates to the number of moles being equal
Therefore, 1.5 moles of FeO 1.5 moles of Fe are produced.
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Name something that has zero thermal energy.
Answer:
When all molecules in a system stop moving completely, there is zero thermal energy
Explanation:
It is impossible to reach though
According to the following reaction, how many moles of hydrobromic acid are necessary to form 0.274 moles bromine?
hydrobromic acid (aq) —>hydrogen (g) + bromine (1)
moles hydrobromic acid
Answer:
0.548 moles of HBr are required
Explanation:
Given data:
Number of moles of hydrobromic acid = ?
Moles of bromine formed = 0.274 mol
Solution:
Chemical equation:
2HBr → H₂ + Br₂
Now we will compare the moles of HBr with Br₂.
Br₂ : HBr
1 : 2
0.274 : 2×0.274=0.548
Thus, 0.548 moles of HBr are required.
If 49.0 g of O2 is mixed with 49.0 g of H2 and the mixture is ignited, what is the maximum mass of water that may be produced?
Answer:
[tex]55.2gH_2O[/tex]
Explanation:
Hello!
In this case, since the reaction between hydrogen and oxygen to produce water is:
[tex]2H_2+O_2\rightarrow 2H_2O[/tex]
When equal masses of each reactant go in contact to carry out the reaction, we can identify the maximum mass of yielded water as the fewest mass yielded by each reactant, just as shown below:
[tex]m_{water}^{by\ H_2}=49.0gH_2*\frac{1molH_2}{2.02gH_2}*\frac{2molH_2O}{2molH_2}*\frac{18.02gH_2O}{1molH_2O} =170gH_2O\\\\m_{water}^{by\ O_2}=49.0gO_2*\frac{1molO_2}{32.0gO_2}*\frac{2molH_2O}{1molO_2}*\frac{18.02gH_2O}{1molH_2O} =55.2gH_2O[/tex]
Thus, since hydrogen yields more water than real, we limit the maximum mass of water to those 55.2 g yielded by oxygen as hydrogen would be in excess.
Best regards!