# Posts by gabriella

Total # Posts: 195

**science**

What do the bone marrow and the epidermis have in commen

**Math**

A shopper keeper sold a total of 15 boxes of pencils on Monday and Tuesday. She still three more boxes on Monday then on Tuesday. There were 12 pencils in each box. How many pencils did she sell on Monday?

**Chemistry**

20 mL of a solution of HCl concentration, neutralized 0,50 g of Na2CO3. What is the Molarity of the acid solution?

**ALGEBRA**

A. OR C. ?

**ALGEBRA**

Factor completely 9x^2 + 42x + 49. A. (3x + 7)(3x − 7) B. (9x − 7)(9x − 7) C. (3x + 7)(3x + 7) D. (9x + 7)(9x + 7) HELP PLEASE DON'T UNDERSTAND

**college algebra**

A piece of machinery valued at $30,000 depreciates at a rate of 10% yearly. How long will it take for it to reach a value of $15,000?

**College Algebra**

The centripetal force of an object moving around a circle varies directly with the square of the speed and inversely as the radius of the object. Suppose the force is 300 N when the speed is 15 m/s and the radius is 5m. What would the force be if the speed was increased to 20 ...

**Advanced functions**

if a car is moving at some speed and then goes twice as far, would the braking distance be twice as far? yes or no? explain

**math**

A mile is 5280 feet. Between which two integers is the elevation in miles?

**Math**

Ndjnsndndnfnf

**Statistics**

The average daily high temperatures in Lawton are approximately normally distributed with a mean of 58 degrees and a standard deviation of 12 degrees. Find the probabilities below: The probability that the high would not exceed 65 degrees on any one day. The probability that ...

**physics**

A car moves from rest with a constant acceleration of 4m/s squared for 5s .IT then continues with the speed attained for10s and then accelerates at 2m/s squared for 10s.A/ SKETCH A SPEED TIME GRAPH FOR THE WHOLE MOTION GIVING YOUR VALUES ON BOTH AXES.B/CALCULATE THE AVERAGE ...

**math**

Suzanna lays the books end to end and finds that the board is the same length as 21 books.how many centimeters long is the board

**math**

It is 74

**language arts**

Me too!!!!

**Pre-Algebra**

Thank you

**Pre-Algebra**

Use the formula d = rt. Find t for r = 46.6 m/h and d = 456.68 m. Show your work. This question is not multiple choice

**English**

Can I also get help with number 5. I have no clue what it is

**English**

7-b 6-d

**English**

Can I get help with the others I got wrong please is 7 b

**English**

what is the correct number to number 6 c or d

**English**

That is the correct question for number 6.

**English**

6.)Which of the following sentences contains a verb that is correctly formed in the perfect tense? a.)Susan is spoken at our club before. b.)Beverly has wanted to be a singer for years. c.)Desmond has love swimming in the ocean. d.)d.)Jake have painted his room three times.

**English**

c b d c d tell me which ones are right then the ones are right then help me with the wrong ones

**English**

4.)Which word or phrase is closest in meaning to the word unanimous? a.)justifies b.)in agreement c.)divided d.)not accurate 5.)Which word is the best choice to complete the following sentence?She didn’t want to get in trouble for breaking the window, so she wrote a note ...

**Pre-Algebra**

I think it is a am I correct

**Pre-Algebra**

5.)What is the best measure of central tendency for the data? Here is the full question to number 5 What answer do you get using this measure? Jessica Jennifer Janice Janine Jessica Jolene Jana a.)mode;Jessica b.)median;Jana c.)mean-Jessica d.)Mode-Janice

**Pre-Algebra**

What do you mean by insufficient information

**Pre-Algebra**

And is the 11 b

**Pre-Algebra**

Thank you. Can you help me with the ones that are wrong. For number 1 83.58*41. The 8 next to the star is underline

**Pre-Algebra**

1.)c 2.)b 3.)b 4.)c 5.)a 6.)a 7.)c 8.)d 10.) b 11.)d Tell me which ones are right and then help me with the wrong ones if any of them are wrong.

**Pre-Algebra**

1.)Identify the underlined place in the decimal number 83.5 8 41.Round the number to that place. a.)thousandths;83.58 b.)hundredths;83.59 c.)hundredths;83.58 d.)thousandths;83.59 2.)Estimate $5.56 + $13.02 using front-end estimation. a.)about $19.60 b.)about $18.60 c.)about $...

**Algebra**

The cruising speed of an airplane is 150 mph. You plan to hire the plan for a 3 hour sightseeing trip. You instruct the pilot to fly as far north as she can and still return to the airport at the end of the allotted time. How far north should the pilot fly if the wind is ...

**Science**

How does dna determine a trait such as eye color

**English**

car = subject for him = prep phrase is = linking verb one = subject compliment of those new GTO's = prep phrase

**AP Chemistry**

Use the Clausius-Clapeyron equation to calculate the temperature at which pure water would boil at a pressure of 367 torr. The heat of vaporization of water is 43105 J/mol at 100◦C. Answer in units of ◦C

**AP Chemistry**

Benzene is a hydrocarbon that is commonly used as a commercial solvent. However, it is carcinogenic; i.e., accumulations in the body can cause cancer. What is the vapor pressure of benzene at 58◦C? The normal boiling point of benzene is 80.0◦C and its molar heat of...

**AP Chemistry**

The rate of effusion of unknown gas X is found to be about 1.5 times that of SF6 gas (MW=146 g/mol) at the same conditions of temperature and pressure. What is the molecular weight of gas X? Answer in units of g/mol

**AP Chemistry**

A 1277 mL sample of nitrogen (N2) was collected by displacement of water at 24 degrees C under a total barometric pressure of 966 torr. What mass of dry nitrogen was collected? The vapor pressure of water at 24 degrees C is 22 torr. Answer in units of g

**AP Chemistry**

Part 1 of 3: An apparatus consists of a 2 L flask containing nitrogen gas at 30 degrees C and 758 kPa, joined by a valve to a 11 L flask containing argon gas at 30 degrees C and 49.7 kPa. The valve is opened and the gases mix. What is the partial pressure of nitrogen after ...

**AP Chemistry**

We drop 30 grams of magnesium into 770 mL of a 4 M HCl solution. What is the maximum volume of dry hydrogen that could be produced by this reaction at STP? Mg(s) + 2HCl(aq)→MgCl2(aq) + H2(g) Answer in units of liters

**AP Chemistry**

Iron pyrite (FeS2) is the form in which much of the sulfur exists in coal. In the combustion of coal, oxygen reacts with iron pyrite to produce iron(III) oxide and sulfur dioxide, which is a major source of air pollution and a substantial contributor to acid rain. What mass of...

**AP Chemistry**

We observe that 5 grams of a gaseous com- pound occupies 2083 mL at 50 degrees C and 574 torr. What is the molecular weight of the compound? Answer in units of g/mol

**AP Chemistry**

A 2.8 gram sample of a gaseous substance occupies 12 L at 47 degrees C and 683 torr. What is the density of the gas under these conditions? Answer in units of g/L

**AP Chemistry**

What pressure would a mixture of 3.2 grams of O2, 6.4 grams CH4, and 6.4 grams of SO2 exert if the gases were placed in a 4.1 liter container at 127 degrees C? Answer in units of atm

**AP Chemistry**

Nitroglycerin is a shock-sensitive liquid that detonates by the reaction 4C3H5(NO3)3(ℓ)-> 6N2(g)+10H2O(g)+12CO2(g)+O2(g) Calculate the total volume of product gases at 201 kPa and 273 degrees C from the detonation of 3.3 lb (1496.9 g) of nitroglycerin. Answer in units...

**AP Chemistry**

To what temperature must a sample of helium gas be cooled from 110 degrees C to reduce its volume from 4.9 L to 0.7 L at constant pressure? Answer in units of K

**AP Chemistry**

what is the pKa of an acid that has a pH of 7.4 at neutralization and has to have 25 mL added to neutralize it

**ap chemistry**

What is the ratio of the molarities of PO3^4- and HPO4^2− ions in a buffer solution having a pH of 13.16? What mass of K3PO4 must be added to 1 L of 0.1 M K2HPO4(aq) to prepare a buffer solution with a pH of 13.16? Answer in units of g What mass of K2HPO4 must be added ...

**ap chemistry**

What is the pH at the equivalence point in the titration of 10.0 mL of 0.56 M HZ with 0.200 M NaOH? Ka = 6.6 × 10−5 for HZ.

**ap chemistry**

What is the pH at the point during a titration when 34 mL of 0.200 M HCl has been added to 29 mL of 0.0500 M NH3 solution? HCl is a strong acid, Kb=1.8×10−5 for NH3. Answer in units of pH

**ap chemistry**

these questions are followups of the original questin posted. How much base much be added to make the solution equalized? Answer in units of mL What is the pKa for this acid?

**ap chemistry**

Calculate the pH at the equivalence point for the titration of a solution containing 150.0 mg of ethylamine (C2H5NH2) with 0.1000 M HCl solution. The volume of the solution at the equivalence point is 250.0 mL. Kb for ethylamine is 4.7 × 10−4.

**ap chemistry**

Calculate the ratio of [NH3]/[NH4+] that gives a solution of pH = 10.60.

**ap chemistry**

How many moles of sodium acetate (NaCH3COO) must be added to 1.000 liter of a 0.500M solution of acetic acid (CH3COOH) to produce a pH of 5.027? The ionization constant of acetic acid is 1.8 × 10−5. Answer in units of mol

**ap chemistry**

The ionization constant of HF is 7.2 × 10−4. What is the molar concentration of H+ in a solution which is 0.353 molar in HF and 0.145 molar in KF?

**ap chemistry**

What mass of solid sodium formate (of MW 68.01)must be added to 125 mL of 0.48 mol/L formic acid (HCOOH) to make a buffer solution having a pH of 4.07? Ka = 0.00018 for HCOOH. Answer in units of g

**ap chemistry**

What is the concentration of hydrogen ions in a solution containing 0.785 M HOCN (cyanic acid) and 0.659 M (NaOCN) (sodium cyanate)? The ionization constant of cyanic acid is 3.5 × 10−4. Answer in units of M

**ap chemistry**

What is the concentration of H+ ions in a buffer solution containing 0.305 M benzoic acid (with ionization constant 6.5 × 10−5)and 0.834 M sodium benzoate (a salt of benzoic acid)?

**ap chemistr**

The ionization constant of HA is 1×10−6. What must be the ratio of [A−] to [HA] for the preparation of a buffer solution with a pH of 5.74?

**ap chemistry**

A buffer solution is made by dissolving 0.45 moles of a weak acid (HA) and 0.23 moles of KOH into 680 mL of solution. What is the pH of this buffer? Ka = 2.4×10−6 for HA.

**AP Chemistry**

If 435 mL of 2.7 molar HCl solution is added to 128 mL of 3.2 molar Ba(OH)2 solution, what will be the molarity of BaCl2 in the resulting solution? Answer in units of M

**AP Chemistry**

If 400 mL of 3.2 molar HCl solution is added to 300 mL of 2 molar NaOH solution, what will be the molarity of NaCl in the resulting solution? Answer in units of M

**AP Chemistry**

A 65 mL sample of a solution of sulfuric acid is neutralized by 46 mL of a 0.14 M sodium hydroxide solution. Calculate the molarity of the sulfuric acid solution. Answer in units of mol/L

**AP Chemistry**

How many moles of NaOH will it take to neutralize 0.77 L of 0.81 M HCl? Answer in units of mol

**AP Chemistry**

50.0 mL of an HCl solution with a pH of 3.5 neutralizes 200.0 mL of a Ca(OH)2 solution. What is the molarity of the Ca(OH)2 solution?

**AP Chemistry**

Which one of the following compounds is not a salt? 1. Ca(ClO4)2 2. Fe(NO3)3 3. Cr(OH)3 4. Na2SO3 5. KMnO4

**algebra 2**

Cube root (x+8)-6=-2

**algebra 2**

3(x-2)^4=24

**AP Chemistry**

A 0.00100 M solution of a weak acid HX is 6% ionized. Calculate Ka for the acid.

**AP Chemistry**

I tried .15 and it said it was incorrect.

**AP Chemistry**

I got the first two parts correct but I can't seem to get the last part. The concentration I got for H3O^+ is 1.151520734e-3. When I plugged that in for the %ion I got 0.1476308633. I typed that into my homework and it said that is incorrect.

**AP Chemistry**

A given weak acid HZ has a Ka=1.7×10−6. What is the H3O+ concentration of a solution of HZ that has a concentration of 0.78 mol/L? What is the pH of this solution of HZ? What is the percent ionization of HZ in this solution? Answer in units of %

**AP Chemistry**

What is the pH of a 0.41 M solution of pyridinium chloride (C5H5NH+Cl−)? (Kb for pyridine is 1.5×10−9.) Answer in units of pH

**AP Chemistry**

Consider the ionization constants cyanic acid (HOCN) : Ka= 3.5×10−4; ammonia (NH3): Kb= 1.8×10−5. A solution of ammonium cyanate (NH4OCN) is 1. acidic, because the cation and the anion hydrolyze to the same extent. 2. acidic, because the anion ...

**AP Chemistry**

Like all equilibrium constants, Kw varies somewhat with temperature. Given that Kw is 7.51×10−13 at some temperature, compute the pH of a neutral aqueous solution at that temperature.

**AP Chemistry**

The pH of a solution of hydrochloric acid is 1.67. What is the molarity of the acid? Answer in units of mol/L

**AP Chemistry**

The ionic substance T3U2 ionizes to form T2+ and U3− ions. The solubility of T3U2 is 4.07×10−20 mol/L. What is the value of the solubility-product constant?

**AP Chemistry**

What is the value of Ksp for Ag2SO4 if 5.70 g is soluble in 1.00 L of water?

**AP Chemistry**

Calculate the solubility product constant for calcium carbonate, given that it has a solubility of 5.3×10^7 g/L of water.

**AP Chemistry**

A solution of AgI contains 1.2 mol/L Ag+. Ksp of AgI is 8.3×10^17. What is the maximum I− concentration that can exist in this solution? Answer in units of mol/L

**AP Chemistry**

Calculate the concentration of Hg2+ ions in a saturated solution of HgS(s). (Ksp=1.7×10^52) Answer in units of mol/L What volume of solution contains one Hg2+ ion? Answer in units of L/ion

**English**

1. C 2. A 3. A these should be correct.

**AP Chemistry**

The system CO2(g) + H2(g)<->H2O(g) + CO(g) is at equilibrium at some temperature. At equilibrium a 4.00 L vessel contains 1.00 mole CO2, 1.00 mole H2, 2.40 moles H2O, and 2.40 moles CO. How many moles of CO2 must be added to the system to bring the equilibrium CO ...

**AP Chemistry**

A mixture consisting of 1 mol of H2O(g) and 1 mol CO(g) is placed in a 11 L reaction vessel at 800 K. At equilibrium, 0.422 mol CO2(g) is present as a result of the reaction CO(g) + H2O(g)<->CO2(g) + H2(g). What is Kc at 800 K?

**AP Chemistry**

The equilibrium constant for the reaction PCl3(g) + Cl2(g)<-> PCl5(g) is 35000 at 760◦C. At equilibrium, the partial pressure of PCl5 was 110 bar and that of PCl3 was 9.98 bar. Calculate the equilibrium partial pressure of Cl2. Answer in units of bar

**AP Chemistry**

At 350 K, Kc= 0.142 for the reaction 2BrCl(g)<-> Br2(g) + Cl2(g) An equilibrium mixture at this temperature contains equal concentrations of bromine and chlorine, 0.049 mol/L. What is the equilibrium concentration of BrCl? Answer in units of M

**AP Chemistry**

At a certain temperature, the equilibrium constant Kc is 0.154 for the reaction 2SO2(g) + O2(g)<-> 2SO3(g) What concentration of SO3 would be in equilibrium with 0.250 moles of SO2 and 0.885 moles of O2 in a 1.00 liter container at this temperature? Note: These latter ...

**AP Chemistry**

The equilibrium constant for thermal dissociation of F2 F2(g)<->2F(g) is 0.300. If initially 1.00 mol F2 is placed in a 1.00 L container, which of the following is the correct number of moles of F2 that have dissociated at equilibrium? 1. 0.130 mol 2. 0.418 mol 3. 0.548 ...

**AP Chemistry**

I got an answer of 0.226, now I need to know what the spontaneous direction of change is. It went from 0.278 to 0.226.

**AP Chemistry**

Analysis of a reaction mixture showed that it had the composition 0.43 mol/L N2, 0.541 mol/L H2, and 0.124 mol/L NH3 at 800 K, at which temperature Kc=0.278 for N2(g) + 3H2(g)<->2NH3(g). Calculate the reaction quotient Qc

**AP Chemistry**

The equilibrium constant Kp is 5.00×10^17 at 25◦C for the reaction C2H4(g) + H2(g)<->C2H6(g). From this information, calculate ∆G0 at 25◦C

**ap chemistry**

What is the activation energy Ea for this reaction? Answer in units of kJ The deltaH is 160 kJ X is at 160 (beginning of reaction) Y is at 300 (end of reaction)

**math**

A circular swimming pool has radius of 15 feet. The family that owns the pool wants to erect a circular fence that is 5 feet away from the pool. Which is the closest to the circumference of the fence they will need? A. 94.2 ft B. 125.6 ft C. 157 ft D. 188.4 ft

**ap chemistry**

Under certain conditions, the reaction 3A + 2B -> 4C was observed to proceed at a rate of 0.00348 M· s−1. What was the corresponding rate of change in reactant A?

**AP Chemistry**

Calculate the standard entropy change for the dimerization of NO2: 2NO2(g)→N2O4(g)at 298 K, if S◦ ∆H◦f J/K·mol NO2(g) 240.06 33.18 N2O4(g) 304.29 9.16 Answer in units of J/K·mol

**AP Chemistry**

This temperature represents the freezing point of ethanol. (Which means delta G = 0) What is the entropy change for the vaporization of 3.3 mol H2O(ℓ) at 100◦C and 1 atm? ∆H= 40700 J/mol. Answer in units of J/K

**AP Chemistry**

Calculate the entropy change when 4.44g of H2 reacts with O2 according to the reaction 2H2(g) + O2(g)→2H2O(ℓ) at 298 K and 1 atm pressure. The stan- dard molar enthalpy of formation of H 2O(ℓ) at 298 K is −285.8 kJ/mol. The corresponding free energy of ...

**AP Chemistry**

Calculate ∆G0 for the following reaction. 4XY + 3Z2−→2Z3X2+ 2Y2 Substance ∆H0f S0kJ/mol J/mol·K XY 205.0 75.0 Y2 −82.0 37.0 Z2 −25.0 78.0 Z3X2 −245.0 137.0 Answer in units of kJ/mol