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.

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

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.

A 0.4672 g sample of pewter (containing tin, lead, copper, and zinc) was dissolved in acid. The precipitate SnO2

In a particular redox reaction, NO2

What is the relationship between the percent of oxygen in a fuel and the amount of energy avaliable per mole of fuel?

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)

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?

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?

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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?

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.

One millimole of Ni(NO3)2 dissolves in 210mL of a solution that is .500M in NH3.

(a) What is the initial concentration of Ni(NO3)2 in the solution?

------> The answer to (a) is .00476 M. I just can't figure out part (b)

(b) What is the equilibrium concentration of Ni^2+(aq) in the solution?

HINT: The Ni^2+ forms a hexammonia complex: Ni(NH3)6^2+. Kf = 5.5 x 10^8.

Oxalic acid, H2C2O4 has acid dissociation constants Ka1 = 5.9 � 10^2 and Ka2 = 6.4 � 10^5. What is the pH after 20.00 mL of 0.0500 M NaOH is added to 5.00 mL of 0.2000 M H2C2O4?

The Answer is 2.8 but I don't know how to get there

Assuming that the smallest measurable wavelength in an experiment is 0.570 fm , what is the maximum mass of an object traveling at 745 m ⋅ s^-1 for which the de Broglie wavelength is observable?

When an excited electron in a hydrogen atom falls from n=7n to n=2, a photon of ultraviolet light is emitted. If an excited electron in an He+ ion falls from n=5, which energy level must it fall to (n1) for ultraviolet light of a similar wavelength to be emitted?

A 2.100×10−2 M solution of glycerol (C3H8O3) in water is at 20.0∘C. The sample was created by dissolving a sample of C3H8O3 in water and then bringing the volume up to 1.000 L. It was determined that the volume of water needed to do this was 999.1 mL . The density of water at 20.0∘C is 0.9982 g/mL.

a.) Calculate the molality of the glycerol solution. Express your answer to four significant figures and include the appropriate units.

b.)Calculate the mole fraction of glycerol in this solution. Express the mole fraction to four significant figures

c.)Calculate the concentration of the glycerol solution in percent by mass. Express your answer to four significant figures and include the appropriate units.

d.)Calculate the concentration of the glycerol solution in parts per million. Express your answer as an integer to four significant figures and include the appropriate units.