[8] What are acids and bases? Describe the two terms giving examples that you commonly use. Explain the term ‘pH’, its equation, and provide a few numbers representing the pH scale! Explain the term ‘Acid Rain’, its formation and its detrimental effect on environment.
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Phosphoric acid is a triprotic acid (Ka1=6.9×10−3Ka1=6.9×10−3, Ka2=6.2×10−8Ka2=6.2×10−8, and Ka3=4.8×10−13Ka3=4.8×10−13).
To find the pH of a buffer composed of H2PO−4(aq)H2PO4−(aq) and HPO2−4(aq)HPO42−(aq), which pKaKa value should be used in theHenderson–Hasselbalch equation?
pKa1Ka1 = 2.16
pKa2Ka2 = 7.21
pKa3Ka3 = 12.32
Calculate the pH of a buffer solution obtained by dissolving 18.018.0 g of KH2PO4(s)KH2PO4(s) and 30.030.0 g of Na2HPO4(s)Na2HPO4(s) in water and then diluting to 1.00 L.
pH=
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Potassium nitrate, KNO3KNO3, has a molar mass of 101.1101.1 g/mol. In a constant-pressure calorimeter, 44.644.6 g of KNO3KNO3 is dissolved in 201201 g of water at 23.00 °C23.00 °C.
KNO3(s)H2O−−→K+(aq)+NO−3(aq)KNO3(s)→H2OK+(aq)+NO3−(aq)
The temperature of the resulting solution decreases to 17.70 °C17.70 °C. Assume that the resulting solution has the same specific heat as water, 4.184 J/(g⋅°C)4.184 J/(g·°C), and that there is negligible heat loss to the surroundings.
How much heat was released by the solution?
What is the enthalpy of the reaction?
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In isolated thylakoid membranes you measure, through the use of molecular probes, a transmembrane potential of delta psi = + 60 mV and a delta pH of 2- (inside acidic) across the thylakoid membrane. A) How much free energy is yielded by moving 1 mole of protons outward through the H+-ATPase under these conditions of delta psi and delta pH? B) If there are 10 c- subunits in the chloroplast ATPase (cFo), how much energy is available to synthesize each ATP?
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[A], M [B], M Δ [C]/ Δ t (initial) M/s
0.215 0.150 5.81 x 10–4
0.215 0.300 1.16 x 10–3
0.430 0.150 2.32 x 10–3
Given the initial rate data for the reaction A + B ? C, determine the rate expression for the reaction.
Please show steps and explain please
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van der Waals Cycles For all cycles in this section, assume that you have exactly 1.000 moles of gas and that the cycle is run reversibly. The known state parameters for the cycle will be given as the reduced temperature Tr T=Tc and reduced pressure Pr P=Pc, where Tc and Pc are the critical temperature and pressure of your assigned diatomic molecule. Assume the gas is a diatomic van der Waals gas. 1. You have a Carnot cycle that begins with an adiabatic expansion from an initial state dened by a temperature of Tr = 1:75 and a pressure of Pr = 2:00 to a pressure of Pr = 1:75. The system then undergoes an isothermal expansion to a pressure of Pr = 1:25, followed by an adiabatic compression and then an isothermal compression back to the initial state. Calculate w, q, ΔU, ΔS, ΔSsur, ΔH, ΔA and ΔG for each step in the cycle and for the total cycle.
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Consider a CSTR used to carry out a reversible isomerization reaction (A↔B) where both the forward and reverse reactions are first-order. Feed is pure A and the reaction is assumed to be elementary. CPa =1255 J/moleºK CPb = 1172 J/moleºK kf = 8.83 x 104 e –6290/T sec-1 kr = 4.17 x 1015 e –14947/T sec-1 where T is in degrees Kelvin (a) Is the reaction exothermic or endothermic? What is the standard enthalpy change for the reaction? (b) What is the equilibrium fraction conversion at 340ºK? (c) What conversion is achieved if t = 480 sec and the reactor temperature is 340ºK? (d) For t = 480 sec, sketch the curve of fraction conversion versus reactor temperature over the range 320 to 370ºK. (e) Derive the equation for the curve describing the energy balance on the CSTR for adiabatic operation. Substitute variables into this expression to obtain a relation between X, Tinlet , and Toutlet. (f) In order to maximize production of B when t = 480 sec, what inlet temperature should be specified?
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A single crystal of a metal is oriented for a tensile test such
that its slip plane normal makes an angle of 64.2° with the tensile
axis. Three possible slip directions make angles of 30°, 48°, and
78° with the same tensile axis.
(a) Which of these three slip directions is most favored?
(b) If plastic deformation begins at a tensile stress of 1.6 MPa (232.1 psi), determine the critical resolved shear stress for this metal
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± Pressure-Based versus Concentration-Based Equilibrium Constants
Part A.) For the reaction
3A(g)+3B(g)⇌C(g)
Kc = 67.6 at a temperature of 287 ∘C .
Calculate the value of Kp.
Part B.) For the reaction
X(g)+3Y(g)⇌3Z(g)
Kp = 1.65×10−2 at a temperature of 209 ∘C .
Calculate the value of Kc.
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these solutions (2-5) will each be in their own 50 mL volumetric flask.
assigned pH for buffer system: 4.75
acid/base pair to use: acetic acid and sodium acetate
| concentration of acetic acid | amount of acid to add | concentration of sodium acetate | amount of base to add | |
|---|---|---|---|---|
| unit | molarity | g or mL (circle one) | molarity | g or mL (circle one) |
|
solution 2 |
0.05 | 0.5 | ||
| solution 3 | 0.10 | 0.5 | ||
| solution 4 | 0.50 | 0.05 | ||
| solution 5 | 0.50 | 0.10 |
Sample calculation for acid (solution 2-5):
Sample calculation for base (solution 2-5):
You will prepare 4 different 50 mL solutions from the table above. Once you have the calculated amount of acid (g or mL) and base (g or mL) in the correct flask, what should you do to finish preparing each solution? Describe the steps you will take to make this solution.
Finally, transfer each solution to a container for storage.
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What is the concentration of each of the following solutions? (a) The molality of a solution prepared by dissolving 25.0 g of H2SO4 in 1.30 L of water (b) The mole fraction of each component of a solution prepared by dissolving 2.25 g of nicotine, C10H14N2, in 80.0 g of CH2Cl2
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Consider a buffer solution that contains 0.25 M C6H4(CO2H)(CO2K) and 0.15 M C6H4(CO2K)2. pKa(C6H4(CO2H)CO2-)=5.41.
1. Calculate its pH
2. Calculate the change in pH if 0.140 g of solid NaOH is added to 190 mL of this solution.
3. If the acceptable buffer range of the solution is ±0.10 pH units, calculate how many moles of H3O+ can be neutralized by 250 mL of the initial buffer.
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The hydrolysis of table sugar (sucrose) occurs by the following overall reaction sucrose + water → glucose + fructose and is first order in sucrose concentration with a rate constant of 3.50 × 10⁻³ min⁻¹. If a 0.500 M solution of sucrose is allowed to react for 345 min, what will be the average rate of production of glucose over that period of time in units of M/min?
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A) What is the pH of a solution created by combining 1.28 mole of HOBr and 0.52 mole NaOH in a 1.00L solution? Ka HOBr = 2.5 x 10-9
B) What is the pH of a buffer made by combining 0.62 moles HOBr with 0.88 moles NaOBr in a 100.00mL solution? Ka HOBr = 2.5 x 10-9
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Part A
Write the anode and cathode reactions that cause the corrosion of iron metal to aqueous iron (II).
Express your answer as a chemical equation. Identify all of the phases in your answer.
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| anode reaction: |
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Part B
Express your answer as a chemical equation. Identify all of the phases in your answer.
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| cathode reaction: |
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Part C
Write the balanced half-reactions involved in the air oxidation of Fe2+(aq) to Fe2O3?3H2O.
Express your answer as a chemical equation. Identify all of the phases in your answer.
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| oxidation reaction: | ||||||
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Part D
Express your answer as a chemical equation. Identify all of the phases in your answer.
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| reduction reaction: |
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