What is the appropriate equation for determining the standard deviation of an analytical result from a calibration curve? Define all symbols used.

1) Suppose 500 mL of an 0.200 molar HCl acid is titrated with 70.0 mL of a 1.00 M NaOH solution. What is the final pH of the solution? The error interval is 0.1 pH units.

2) Suppose 500 mL of 0.100 M benzoic acid, which has a pK_a of 4.201, solution is titrated with 75.0 mL of a 1.00 M NaOH. What is the final pH? The error interval is +/- 0.2 pH units.

So i have my chemistry exam next week and this is a question from the practice test. I am wondering more of the how/why for this question than just the answer? How do you tell what is soluable and what isn't how to know what the reaction is gonna be? Is there any easier way to think about this than memorizing the solubility chart. And even with he chart memorized... how do i answer a question like this, am i looking for slightly soluble?

When aqueous solutions of ________ are mixed, a precipitate forms.

A) NiCl2 and AgNO3

B) NaCl and KBr

C) K2SO4 and CrCl3

D) KOH and AgNO3

E) Li2CO3 and KCl

more questions I'm concerned about... again not looking for the answers just like how to go about understanding the solubility and reactions between substances?

Which of the following is an oxidation-reduction reaction? A) HCl (aq) + NaOH (aq) → H2O (l) + NaCl (aq) B) AgNO3 (aq) + HCl (aq) → AgCl (s) + HNO3 (aq) C) BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaCl2(aq) D) Mg (s) + 2AgNO3 (aq) → 2Ag (s) + Mg(NO3)2 (aq) E) H2CO3 (aq) + Ca(NO3)2 (aq) → 2HNO3 (aq) + CaCO3 (s)

4) The balanced reaction between aqueous nitric acid and aqueous strontium hydroxide is ________. A) 2HNO3 (aq) + Sr(OH)2 (aq) → 2H2O (l) + Sr(NO3)2 (aq) B) HNO3 (aq) + Sr(OH)2 (aq) → Sr(NO3)2 (aq) + H2 (g) C) HNO3 (aq) + Sr(OH)2 (aq) → H2O (l) + Sr(NO3)2 (aq) D) HNO3 (aq) + SrOH (aq) → H2O (l) + SrNO3 (aq) E) 2HNO3 (aq) + Sr(OH)2 (aq) → Sr(NO3)2(aq) + 2H2 (g)
5) In which reaction does the oxidation number of hydrogen change? A) HCl (aq) + NaOH (aq) → NaCl (aq) + H2O (l) B) 2Na (s) + 2H2O (l) → 2NaOH (aq) + H2 (g) C) CaO (s) + H2O (l) → Ca(OH)2 (s) D) 2HClO4 (aq) + CaCO3 (s) → Ca(ClO4)2 (aq) + H2O (l) + CO2 (g) E) SO2 (g) + H2O (l) → H2SO3 (aq)

If we mix 40.0 mL of 3.00 M Pb(NO3)2 (aq) with 20.0 mL of 2.00 x 10-3 M NaI (aq), does PbI2 (s) precipitate from solution? I yes, calculate how many moles of PbI2 (s) precipitate and the values of [Pb2+], [I-], [NO3-], and [Na+] at 25 C at equilibrium?

Given that the solubility constants of HgSO4 and PbSO4 are 6.6x10-7 and 1.6x10-8 respectively, determine the cell potential when the electrolyte is saturated with both
salts at 298 K.

1) Calculate the number of mL of water in 1.00 cubic feet of water.

2) The radius of an AI atom is 0.143 nm. How many AI atoms would have to be laid side-by-side to give a row of atoms 1.00 inch long? (Assume atoms are spherical in shape.)

3) A given point on the moon is 240,000 mi from Earth. How long does it take for light from Earth to reach a reflector at that point on the moon and then return to the Earth if the speed of light is 3.00 * 10^8 m/s?

4) A spherical steel ball has a mass of 3.475 g and a diameter of 9.40 mm. What is the density of the steel in g/cm^3? The volume of a sphere = (4/3)pir^3

The reaction 2NO(g) + Cl₂(g) --> 2NOCl(g) obeys the rate law rate = k [NO]² [Cl₂]. The following mechanism is proposed:

NO (g) + Cl₂ (g) --> NOCl₂(g)

NOCl₂(g) + NO (g) -->2NOCl (g)

a) What would the rate law be if the first step was rate determining?

b) Based on the observed rate law, what can be concluded about the relative rates of the 2 reactions?

A researcher was attempting to quantify the amount of dichlorodiphenyltrichloroethane (DDT) in spinach with gas chromatography using a chloroform internal standard. To begin, the researcher examined a sample containing 9.65 mg/L DDT standard and 2.40 mg/L chloroform as the internal standard, producing peak areas of 3589 and 6209, respectively.

Then, the researcher collected 6.53 g of spinach, homogenized the sample, and extracted the DDT using an established method (assume 100% extraction), producing a 3.24 ml volume of unknown sample. The researcher then prepared a sample that contained 1.00 ml of the unknown sample and 1.50 ml of 12.90 mg/L chloroform, which was diluted to a final volume of 25.00 ml. The sample was analyzed using GCMS, producing peak areas of 8017 and 13637 for the DDT in the unknown and the chloroform, respectively.

Calculate the DDT concentration in the spinach sample. Express the final answer as milligrams of DDT per gram of spinach.

concentration of DDT:

Suppose 10.00 mL of 0.200 M HCl is added to an acetate buffer prepared by dissolving 0.100 mol of acetic acid and 0.110 mol of sodium acetate in 0.100 L of solution. What are the initial and final pH values? What would be the pH if the same amount of HCl solution were added to 125 mL of pure water? Initial pH = Final pH =

Gaseous butane CH3CH22CH3 will react with gaseous oxygen O2 to produce gaseous carbon dioxide CO2 and gaseous water H2O. Suppose 4.65 g of butane is mixed with 5.3 g of oxygen. Calculate the maximum mass of carbon dioxide that could be produced by the chemical reaction. Be sure your answer has the correct number of significant digits.

I have a problem, and I have the answer but I don't know where the solution comes from. ( I have to be able to solve these myself so please help me by answering the questions about the problem.)

Here is the answer given to me by the professor:

What is the density of SF₄ vapor at 650 torr and 100 C?

650 torr (1atm/760 Torr)=0.855atm 100C=373K

PV=nRT n/v=P/RT= 0.855atm/0.8206l-atm/molek) (373)=0.0279 mole/l

M.W. of SF₄=108.1 gm/mole

Density=mass/volume 0.0279 mole/l(108.1gm/mole)

Answer =3.02 gm/l

Here are my questions:

Where did the 760 torr come from? Where did the 0.855atm come from? What is the abbreviation m.w. ? I basically need a step by step explanation of this problem because I dont understand how the answer was achieved.