# ?

### Titration problem! Please help! :(?

For the titration of 25.0 mL of 0.20 M hydrofluoric acid with 0.20 M sodium hydroxide, determine the volume of base added when pH is a) 2.85, b) 3.15, and c) 11.89.

The answers are: a) 8.3 mL b)12.5 mL and c) 27.0 mL.

I want to know how to solve the problems, especially part C.

Thanks

1 AnswerChemistry9 years ago### What is the bond angle in a square planar geometry?

square planar is the molecular geometry of octahedral. It has two lone pairs. What is the angle between the bonds?

Chemistry1 decade ago### what is a dipositive ion?

a dipositive ion has the ground state electron configuration:

1s2 2s2 2p6 3s2 3p2. what is the element?

the answer's not silicon.

1 AnswerChemistry1 decade ago### inverse trig functions??!?

how do u solve an equation like the following:

arccos(cos(-π/2))

1 AnswerMathematics1 decade ago### Graphing Calculator ugent question?

How do u list a set of numbers in L1 in STAT? I want to number from 1 to 30, but i want an easier way to put in the numbers. I know that u have to highlight L1 at the top and do something after that but i cant figure it out. plz help

p.s. i have TI-84 Plus Texas Instrument

1 AnswerMathematics1 decade ago### AP Calculus Derivative?

f(x)=cotx/sinx

Ans: (-1-cos^2x)/sin^3x

Please explain how to derive the answer.

1 AnswerMathematics1 decade ago### CAlculus AB derivatives?

find d^2y/dx^2 in terms of x and y.

X^2 - Y^2 = 16

Ans: -16/y^3

Please explain how to derive the answer.

1 AnswerMathematics1 decade ago### PHYSICS QUESTION POR FAVOR?? A new antiterrorist technique detects the differences in electromagnetic waves...

A new antiterrorist technique detects the differences in electromagnetic waves emitted by humans and by weapons made of metal, plastic, or ceramic. One possible range of wavelengths used with this technique is from 2-5 mm. Calculate the associated range of frequencies.

1 AnswerPhysics1 decade ago### Answer my physics question por favor!! If a cordless phone uses a frequency of 900 MHz and can operate up...?

If a cordless phone uses a frequency of 900 MHz and can operate up to 60 meters away from its base, how many wavelengths of the radio waves can fit between your ear and a base 60 meters away?

1 AnswerPhysics1 decade ago### Why do photographers use red light in their darkrooms?

4 AnswersPhysics1 decade ago### Great question about circuits!!!??

You have four light bulbs, light bulbs one, two, three, and four. All have the same intensity. Bulb one is unscrewed causing only bulb one to go out. Now, bulb two's intensity is 30% greater than it was originally. Bulbs three and four each have 2/3 of their original intensity. Based upon this information, how are the four bulbs wired?

3 AnswersPhysics1 decade ago### Circuits question??

you have three light bulbs. two are connected in parallel. this parallel combination is connected in series with the third light bulb. describe the relative intensity of each light bulb??

feel free to include examples ;)

1 AnswerPhysics1 decade ago### Another of my super duper chem questions ;)?

ok so, For the reaction 14, 6 C ---> e- + ? , the missing product is _____.

the 14 is on the top of the C and the 6 is on the bottom, which i believe the 14 is the atomic mass and the 6 is the atomic number(# of protons).

and so explain is the carbon gaining an electron?

3 AnswersChemistry1 decade ago### Solve this chemistry question!!! It's fun =)?

just kidding but here's the question:

how many moles of HCL(g) will completely react with 5.00 grams of magnesium hydroxide?

please explain how to get the answer ( i know how to write the balanced equation but that's it).

4 AnswersChemistry1 decade ago### How can you tell if a product in an equation is a solid?

for example in this question it asks to: identify the solid product that forms when 0.1 M CoCl2 (aq) and 0.1 M Na2S (aq) are mixed.

i know how to write the balanced equation but how can you tell if something is a precipitate or a liquid?

i hope i make sense

4 AnswersChemistry1 decade ago### Another magnífico chemistry question?

how many grams of NaOH are required to prepare 5.0 * 10^2 mL of a 0.80 M sodium hydroxide solution?

please explain how you get the answer

3 AnswersChemistry1 decade ago### Chemistry question?? ayúdeme por favor?

consider: H3O+ (aq) + OH- (aq) <==> 2 H2O

if the initial concentrations are

[ H3O+ (aq) ] = 0.1 M

[ OH- (aq) ] = 0.7 M

at equilibrium, [ OH- (aq) ] will be_____.

the answer is 0.6 M

please explain in detail how you get the answer.

1 AnswerChemistry1 decade ago