# Posts by Summer

Total # Posts: 338

**Chemistry**

If there are 0.625 g of NaCl left in a beaker that originally contained 75.0 mL of saltwater, what must have been the molar concentration of the original solution? The molar mass of NaCl is 58.44 g/mol.

**math mental math**

shelley spent 17 min washing the dishes. she spent 38 min cleaning her room. explain how you can use mental math to find how long shelley spent on the two tasks?

**Chemistry**

What kind of reaction does it cause though?precipitate reaction, released gas reaction, or no reaction. you answered yes, no, yes but didn't explain what reaction it is.

**Chemistry**

Will the following reactions mixed together cause a precipitate reaction, released gas reaction, or no reaction. Ba(NO3)2 mixed with NaCl Ba(NO3)2 mixed with HCl Ba(NO3)2 mixed with Na2CO3 Ba(NO3)2 mixed withNa3SO4 also Ba(NO3)2 is soluble and a solid and HCl is a gas. Is ...

**CHEMISTRY (IODINE VALUE-continuation)**

y question is about Determination of Iodine Value in Fats & Oils experiment. I can't seem to get the right IV for coconut oil (Iv = 7-11 range). I followed the procedure used by American Oil Chemists Society, but still I'm getting an IV value of around 1. The volume of...

**CHEMISTRY (PLEASE HELP)**

My question is about Determination of Iodine Value in Fats & Oils experiment. I can't seem to get the right IV for coconut oil (Iv = 7-11 range). I followed the procedure used by American Oil Chemists Society, but still I'm getting an IV value of around 1. The volume ...

**Math**

Two concentric circles have radii of 24cm and 26cm. What is the length of the chord that is tangent to the inner circle? I don't understand the tangent, like where do I draw the line?

**Physics**

A bird lands on a bare copper wire carrying a current of 27 A. The wire is 8 gauge, which means that its cross-sectional area is 0.13 cm2. (a) Find the difference in potential between the bird's feet, assuming they are separated by a distance of 7.2 cm.

**Physcis**

A bird lands on a bare copper wire carrying a current of 27 A. The wire is 8 gauge, which means that its cross-sectional area is 0.13 cm2. (a) Find the difference in potential between the bird's feet, assuming they are separated by a distance of 7.2 cm.

**social studies**

Let's all dab on this 100%

**MATH PLEASE HELP MRS.SUE!**

Can someone answer the question that are not answered.

**science**

The answers are all correct straight above

**Math**

When an engineer inspects a pipeline she notices a high water mark. How much space is there between the high water level and the top of the pipe, to the nearest hundredth. The diameter of the pipe is 1.2m and the horiztonal distance across the surface of the water is 80 cm.

**Algebra**

A boy was sent with $2.10 to buy oranges. He found the price 3 cents higher per dozen than he had expected to pay, and so he bought 6 fewer oranges than he had intended to buy and received 1 cent in change. How much did he pay for a dozen oranges?

**science**

To increase friction

**Algebra**

A man drove his automobile to New York, a distance of 550 miles, at a certain average rate. He returned from New York at the rate of 11 mph more. The entire trip required 22.5 hours. What were his rates returning and going?

**Algebra Word Problem**

Thank you so much!

**Algebra Word Problem**

A number of men subscribed a certain amount to make up a deficit of $100 but 5 men failed to pay and thus increased the share of the others by $1 each. Find the amount that each man paid.

**Algebra**

The time required for a trip 108 miles downstream on a steamer is 3 hours less than the time required for the upstream trip. A boat whose rate is 6 miles per hour less than that of the steamer required 9 hours more for the upstream trip than for the downstream trip. Find the ...

**math**

????

**Eric**

I think they are.

**Math**

Omg... I am not the only one who got this homework... I don't understand it

**Economics**

Suppose you are the manager of a California winery. How would you expect the following events to affect the market equilibrium price you receive for a bottle of wine? Please state the shift (leftward or rightward) of demand or supply. a. The price of comparable French wines ...

**Science ~ Structures and Properties of Matter**

Sorry, but it doesnt seem to be working for me. Mabey because of my computer, but I need to know the answer. Somebody help me!!!!!

**Chemistry**

To neutralize a 0.5192 g organic acid, 44.0 mL NaOH solution (1.00 ml ~ 1.12 mL HCl ~ 0.0100 g CaCO3) is required. What is the equivalent weight of the organic acid?

**Chemistry**

What will be the volume of concentrated H2SO4 that must be added to 155 mL of 0.1996 N H2SO4 in a 500 mL volumetric flask so that the resulting solution will be 6.5210 M? pls. explain.

**Chemistry**

Calculate the volume of 2.503 N HNO3 added to 100 mL of HCl in order to prepare 1.1251 N acid solution from the following data: 58.96 mL NaOH will neutralize 2.521g of potassium tetroxalate and 45.57 mL of HCl will neutralize 53.0 mL of the NaOH solution.

**Chemistry**

How to know their mass? Is is their molecular mass?

**Chemistry**

Calculate the % Na2CO3 and % BaCO3 in a 0.2005g sample which requires 28.0mL of 0.9990 N acid for complete neutralization.

**Chemistry**

To what volume must 1580mL of 0.2005 N solution be diluted so that the resulting solution will be 0.1899 M? How much water will be needed in the dilution?

**Chemistry**

A 0.2299 N acid is prepared by mixing 100 ml of 0.1234 N H2SO4 and 0.3200 N HCl. How much HCl is needed in the preparation of the solution?

**Algebra**

If 9876^2=97,535,376 Find the value of 9877^2 and (9874)(9878) without using a calculator

**Chemistry**

The dipole moment (μ) of HBr (a polar covalent molecule) is 0.851D (debye), and its percent ionic character is 12.6% . Estimate the bond length of the H−Br bond in picometers.

**Chemistry**

The dipole moment (μ) of HBr (a polar covalent molecule) is 0.851D (debye), and its percent ionic character is 12.6% . Estimate the bond length of the H−Br bond in picometers.

**9th algebra**

the sum of the digits of a two place fraction is 9. When its digits are reversed, the new fraction exceeds the original by 0.09. Find the original fraction.

**Algebra**

Oh yes! I figured it out by myself.

**Algebra**

Thanks a lot!

**Algebra**

1.The ratio of nickels to dimes to quarters in 3 : 8 : 1. If all the coins were dimes, the amount of money would be the same. Show that there are infinitely many solutions to this problem. 2.A grocer wants to make a mixture of three dried fruits. He decides that the ratio of ...

**9th algebra**

1.Jeff can weed the garden in 4 h. His wife takes the same amount of time. After they worked for 1 hr, their son helped them finish in 1/2 h. H long would it have taken Rory by himself to weed the garden?

**Finance**

a. If upon retirement in 20 years Simon plans to invest $400,000 in a fund that earns 5%, what is the maximum annual withdrawal he can make over the following 15 years?

**Grammar Please hurry please**

b a c b a b a c

**physics**

The brakes of a truck cause it to slow down by applying a retarding force of 2350 N to the truck over a distance of 817 m. What is the work done by this force on the truck?

**AP Chemistry**

An unknown metal M forms a soluble compound, M(NO3)2. A solution of M(NO3)2 is electrolyzed. When a constant current of 2.5 amperes is applied for 35 minutes, 3.06 grams of the metal M is deposited. Calculate the molar mass of M and identify the metal.

**Chemistry**

A cell has a standard emf of +0.177 V at 298 K. What is the value of the equilibrium constant for the cell reaction a) if n=1? b) if n=2?

**3rd grade**

Well you have 30 cents in dimes. a quarter is 25 cents so you have five cents extra. you can ask for change for one dime or trade with someone your dime for two nickels

**3rd grade math**

regroup the ten ones as 1 ten again

**Chemistry**

The calculated Ka in one of my previous comments is from a different question- it's not related to this problem.

**Chemistry**

...H2A->...H+..+..HA- ...x.......0......0 -.00708..+.00708..+.00708 x-.00708...00708...00708 K1=.017=(.00708)^2/x-.00708 x=.01 The acid is .01M. There are 250 mL. There are .205g of acid. .205g=.0025mol .205/.0025=82

**Chemistry**

Yes, the intrepid hero post was mine- these are both extra credit problems from our class and I'm having some trouble with this unit. For that one the Ka I came up with was 2.22*10^-5. As for this problem, your logic makes sense but I'm unsure how to calculate (A^2-) ...

**Chemistry**

I've calculated the molar mass as 82g/mol, but I can't figure out how to get the dissociation constant.

**Chemistry**

A 205 mg sample of a diprotic acid is dissolved in enough water to make 250.0 ml of solution. The pH of this solution is 2.15. A saturated solution of calcium hydroxide (Ksp= 1.3 x 10-6) is prepared by adding excess calcium hydroxide to water and then removing the undissolved ...

**Algebra**

First, find the greatest common factor of the two terms- in this case, 21. Then divide each term by the GCF. 42q/21=2q and -21/21=-1 So, 21(2q-1)

**Biology**

Most likely the one with the most descendants. Evolutionary science generally deals with the passing on of genes, and that frog would have reproduced the most and would therefore have been the most successful.

**Biology**

The mice would be half heterozygous for black, and half white.

**Grammar...**

Sorry, our answers posted at the same time. I didn't mean to seem excessively insistent.

**Grammar...**

I think that the apostrophe would be redundant

**Grammar...**

The "that of" makes the sister possessive- no need to be possessive twice.

**Grammar...**

No- It would be: Her coat is different from that of her sister.

**Chemistry**

It's actually 4.5*10^-6. 5=pKa+log(10/22.22)

**Chemistry**

I plugged those numbers into the HH equation and came up with 2.22*10^-5 for the Ka. Does that sound right?

**Chemistry**

At the first point where he stopped and measured the pH, the H+ ion concentration is 1*10^-5 and the OH- ion concentration is 1*10^-9. This is as far as I've gotten, I can't figure out what to do with this information.

**Chemistry**

A very old and tired , grey haired AP Chem instructor wanted to determine the Ka of an unlabelled monoprotic acid in his stockroom. He dissolved an unknown amount of acid in an unknown amount of water and proceeded to titrate the sample with a solution of NaOH of unknown ...

**Algebra**

To find the y-intercept, plug in 0 for y and solve for x. 0=2x+2 2x=-2 x=-1 (0,-1) To find the x-intercept, plug in 0 for x and solve for y. y=2(0)+2 y=2 (2,0)

**Physics2**

"The heat engine uses 1.00x10^-2 mol of a diatomic gas as the working substance. Determine the temperatures at the 3 points." From 1-2, it's an adiabatic process and the constants are (P)(V^(7/5)) or (T)(V^(2/5)). From 2-3, it's an isobaric process with V/T ...

**Physics**

Draw an open circuit that consists of 2 sets of 2 cells connected in series, connected in [arallel with each other. Add a variable resitance R1 in series with a set of 3 light bulbs r2, r3, r4 in parallel with each other. Insert an ammeter and a voltmeter in the circuit

**Algebra**

x+y+z=2 4x+5y+2=12 2x=4 solve using substitution

**math**

valerie earns $25 a day plus $3 for each dog she washes. make a function table to show the relationship between the number of dogs she washed d and the total amount earned t in one day. write an equation to represent the situation.

**statistics**

Refer to the Baseball 2012 data, which report information on the 30 Major League Baseball teams for the 2012 season. a. At the .05 significance level, can we conclude that there is a difference in the mean salary of the teams in the American League versus teams in the National...

**7th grade math Ms. Sue please check**

im stuck on 9

**Physics**

what is a planes velocity if ithas anair speed of 18 and there is a 30 km/h wind blowing south

**Social Studies**

i agree that b is right cause A and c would not work

**physics**

What is the direction of a person that walks 3.0-km North and 4.0-km East?

**physics**

What is the direction of a person that walks 6.0-km North-East, 4.0-km East, and 6.0-km South?

**math**

the manager of a take out pizza parlor needs to hire pizza makers and cahiers for the evening shift. the total number of employees of both kinds can be at most 16, and the ratio of cashiers to pizza makers must be at least 3 to 5. Also, each pizza maker can answer 12 phone ...

**Math**

It took Markus half an hour to drive home from work.He averaged 34 miles per hour. How far does Markus live from work?

**stats**

611

**Chemistry**

Iron (III) oxide is formed when iron combines with oxygen in the air. How many grams of Fe2O3 are formed when 16.7 g of Fe reacts completely with oxygen? a. 12.0g b. 23.9g c. 47.8g d. 95.6g

**CHEMISTRY**

It tells us that there isn't much product but a lot of reactant. It is mostly reactants.

**math**

if 34 baby boys were born in a week and that was 54% how many girls were born in that week

**math**

Solve for X 0.0421=0.0015-x/0.025+1/2x PLEASE HELP!!!

**Pre-Algebra**

x=(-9,0) y=(0,-6)

**Inferential Statictics**

Welsh, Davis, Burke, and Williams (2002) conducted a study to evaluate the effectiveness of a carbohydrate-electrolyte drink on sports performance and endurance. Experienced athletes were given either a carbohydrate-electrolyte drink or a placebo while they were tested on a ...

**math**

Q=3x^2+4y^2 if x+y=7 what is minimum value for Q. I have absolutely no idea how to solve this problem.

**chemistry**

if we combust 4.23 x 10^24 molecules of propane how many grams of carbon dioxide and water you will produce ?

**Chemistry**

What is the concentration of SO3^2- in a 0.043 M solution of Sulfurous acid (H2SO3) in water? The value of Ka1 for H2SO3 is 1.300 x 10-2 and the value of Ka2 is 6.300 x 10-8.

**Chemistry**

I'm doing online chemistry homework, and the site keeps telling me I have the wrong answer, but I'm not sure what I'm doing wrong. please help? What is the pH of a 0.089M solution of phosphorous acid (H2PHO3) in water? The value of Ka1 for H2PHO3 is 1.600 E-2 and ...

**Chemistry**

Oops, sorry. I understand now, thank you.

**Chemistry**

What would the Ka for this be?

**Chemistry**

A solution that contains 2.047 x 10^-1 M of acid, HA, and 1.808 x 10^-1 M of its conjugate base, A-, has a pH of 4.196. What is the pH after 1.629 x 10^-3 mol NaOH is added to 5.961 x 10^-1 L of this solution?

**Chemistry**

A chemist is given an unknown base. She finds that a 1.0461 M aqueous solution of this base has a pH of 13.065 at 25oC. What is the value of Kb for this unknown base ?.

**Chemistry**

How many mL of a solution of NaOH with pH equal to 1.395 x 101 do you need to mix with pure water to obtain 399 mL of a final solution with pH equal to 9.066 ?

**Chemistry**

What is the pH of a 0.051 M solution of Phosphorous acid (H2PHO3) in water? The value of Ka1 for H2PHO3 is 1.600 x 10-2 and the value of Ka2 is 7.000 x 10-7.

**Chemistry**

Thank you

**Chemistry**

What is the [H+] in a 0.98 M solution of formic acid? The Ka of formic acid is 1.8 x 10-4

**Chemistry**

0.100 M

**Chemistry**

Consider the titration of 80.0 mL Ba(OH)2 by 0.400 M HCl. Calculate the pH of the resulting solution after the following volumes of HCl have been added. a.) 0.0 mL *Which molecular equation do I use? b.) 20.0mL Ba(OH)2__+2HCl_+=>+_BaCl2_+____2HOH 80.0 mL__20.0mL 0.100M___0....

**Chemistry**

What is the balanced equation for Ba(OH)2 + HCl?

**Chemistry**

The reaction describing the formation of ozone from oxygen is shown below. 3 O2(g) <--> 2 O3(g) Calculate Grxn at 288 K for this reaction in a flask where [O2] = 3.419 x 10-2 M and [O3] = 5.783 x 10-4 M. Assume G° = 326 kJ. Use molarity to construct the reaction ...

**Chemistry**

For the reaction: 2 NO(g) + 1 O2(g) <--> 2 NO2(g) Calculate K, the equilibrium constant, from thermodynamic data at 281 K. (Hint #1: Assume that S and H do not change with temperature.) (Hint #2: Work in J/mol)

**Chemistry**

Find delta G knot for the following reaction: 2Ch3OH(l) + 3O2(g) --> 2CO2(g) + 4H2O(g)