In a bromine-producing plant, how many liters of gaseous elemental bromine at 277?C and 0.935 atm are formed by the reaction of 450. g of sodium bromide and 205 g of sodium bromate in aqueous acid solution? (Assume no Br2 dissolves ad that sulfuric acid is present in large excess.)
5NaBe+NaBrO3+3H2SO4 -> 3 Br2+3Na2SO4+3H2O
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Calculate the pH of the solution that results from each of the following mixtures.
55.0 mL of 0.16 M HCHO2 with 75.0 mL of 0.13 M NaCHO2
125.0 mL of 0.11 M NH3 with 250.0 mL of 0.11 M NH4Cl
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C6H14(l) + Br2(l) + light → C6H13Br(l) + HBr(g) How do I explain this reaction?
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Phosphorus pentachloride decomposes according to the chemical equation PCL5(g)<--->PCl3(g)+Cl2(g). Kc=1.80 at 250 C. A 0.220 mol sample of PCl5(g) is injected into an empty 3.00 L reaction vessel held at 250 �C. Calculate the concentrations of PCl5(g) and PCl3(g) at equilibrium.
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23.balance Al2O3(s)+NaOH(i)+Hf(g)--> Na3AlF6+H2O(g)
a. If 11.1 kilograms of Al2O3(s), 59.4 kilograms of NaOH(l), and 59.4 kilograms of HF(g) react completely, how b. many kilograms of cryolite will be produced?
c. Which reactants will be in excess?
What is the total mass of the excess reactants left over after the reaction is complete?
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A. You mix a 125.5 mL sample of a solution that is 0.0111 M in NiCl2 with a 183.0 mL sample of a solution that is 0.225 M in NH3
After the solution reaches equilibrium, what concentration of Ni2+(aq) remains? (Formation constant is Kf=2.0×108.)Express your answer with the appropriate units.
B. A 120.0 −mL sample of a solution that is 2.7×10−3 M in AgNO3 is mixed with a 230.0 −mL sample of a solution that is 0.10 M in NaCN.
After the solution reaches equilibrium, what concentration of Ag+(aq) remains?
Express your answer using two significant figures.
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Classify each statement about effective nuclear charge, Zeff, as true or false.
-Effective nuclear charge increases from left to right across a period on the periodic table
-Across a period, as Zeff increases, atomic size increases
-in a N atom, a 1s electron has a great Zeff than a 2s electron
-Effective nuclear charge does not depend on the number of electrons present in an atom
-Electrons in a s orbital are more effective than those in other
orbitals at shielding other electrons from the nuclear charge
-a 1s electron in a B atom has a smaller Zeff than a 1s electron in
a Be atom
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A beaker with 125 mL of an acetic acid buffer with a pH of 5.00 is sitting on a bench top. The total molarity of acid and conjugate base in this buffer is 0.100 M. A student adds 8.90 mL of a 0.350 MM HCl solution to the beaker. How much will the pH change? The pKa of acetic acid is 4.760.
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A 0.4672 g sample of pewter (containing tin, lead, copper, and zinc) was dissolved in acid. The precipitate SnO2
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What is the relationship between the percent of oxygen in a fuel and the amount of energy avaliable per mole of fuel?
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Given the following thermodynamic reactions: CaO (s) + Cl2 (g) ---> CaOCl2 delta H° = -110.9 KJ/ H20 (l) + CaOCl2 (s) + NaBr (s) ---> 2NaCl (s) + Ca(OH)2 (s) + Br2 (l) delta H° = -60.2 KJ/ Ca(OH)2 (s) ---> CaO (s) + H2O (l) delta H° = +65.1 KJ. Calculate the value of delta(Δ)H° (in kilojoules) for the reaction 1/2 Cl2 (g) + NaBr (s) ---> NaCl (s) +1/2 Br2 (l)
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Lithium Nitrogen reacts to form Li3N. A 4.0g sample of lithium is reacted with 2.5g of nitrogen. What weight of what substance remains unreacted?
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3.Phosphate-buffered saline (PBS) is a buffer solution commonly used in biological research. Most formulations contain a mixture of KCl and NaCl buffered to a pH of 7.40 using phosphate-containing compounds.
a.The following reagents are available in your lab. Choose the correct reagents and calculate the volumes necessary to prepare exactly 5.0 L of a phosphate buffer with a pH of 7.40.
0.100 M H3PO4 0.150 M Na2HPO4
0.200 M KH2PO4 0.120 M Na3PO4
b.Commercial PBS solutions are typically prepared by dissolving solid reagents in water and then adjusting the pH to 7.40 using HCl. The formulation shown below is for the preparation of 10.0 L of a PBS solution. What is the pH of this solution and how many moles of HCl must be added to
adjust the pH to 7.40?
Component |
Mass (g) |
NaCl |
80.0669 |
KCl |
2.0129 |
Na2HPO4 |
14.1960 |
KH2PO4 |
2.4496 |
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Question
1. When NO2 is bubbled into water, it is completely converted to HNO3 and HNO2 according to the reaction shown below. Calculate the pH and the molar concentrations of all dissolved species (H3O+, OH–, HNO2, HNO3, NO2–, and NO3–) in a solution prepared by bubbling 4.601 g NO2 through 2.00 L of water.
2NO2(g) + H2O(l) → HNO3(aq) + HNO2(aq)
2. 12.6-g sample of Na2A (molar mass = 126 g/mol) is dissolved enough water to produce 1.00 L of solution. The pH of this solution is 9.85 and the equilibrium concentration of H2A is 1.0 × 10–12 M. Determine the values of pKa1 and pKa2 for H2A
3.Phosphate-buffered saline (PBS) is a buffer solution commonly used in biological research. Most formulations contain a mixture of KCl and NaCl buffered to a pH of 7.40 using phosphate-containing compounds.
a.The following reagents are available in your lab. Choose the correct reagents and calculate the volumes necessary to prepare exactly 5.0 L of a phosphate buffer with a pH of 7.40.
0.100 M H3PO4 0.150 M Na2HPO4
0.200 M KH2PO4 0.120 M Na3PO4
b.Commercial PBS solutions are typically prepared by dissolving solid reagents in water and then adjusting the pH to 7.40 using HCl. The formulation shown below is for the preparation of 10.0 L of a PBS solution. What is the pH of this solution and how many moles of HCl must be added to
adjust the pH to 7.40?
Component |
Mass (g) |
NaCl |
80.0669 |
KCl |
2.0129 |
Na2HPO4 |
14.1960 |
KH2PO4 |
2.4496 |
4. Consider the potentiometric titration of 25.0 mL of 0.200 M selenious acid (H2SeO3) with 0.250 M NaOH.
a. Identify the primary selenium-containing species present at each point in the titration (A – E) shown below. Then sketch the titration curve, identifying points A – E. Make sure to appropriately label the axes.
Point |
NaOH Added (mL) |
Se-Containing Species |
|
A |
0.00 |
||
B |
10.00 |
||
C |
20.00 |
||
D |
25.00 |
||
E |
40.00 |
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