Sunday
December 11, 2016

# Posts by Mara

Total # Posts: 101

Chemistry
calculate the volumes of acetone and ethanol that was used to mix together in order to produce 1 litre (1000ml) of equimolar mixture. helpful notes are, ethanol Mr=46 and a density (20 degrees C)=0.789g/ml, acetone Mr=58 and density (20 degrees C)=0.793g/ml
October 24, 2016

Math
How to do the coffee shop has nine pies
September 22, 2016

Math
How do you solve it in pictures
September 22, 2016

Government
Please check my answer~ What is the key difference between a federal government and a confederate government? A.In a federal government, local governments have the most power. In a confederate government, a central government has the most power. B.In a confederate government ...
September 8, 2016

German
Can someone please check my German? _____ du die Fragen? A.Beantwortest B.Fragtest <<< C.Weiß D.Lest Wir lernen über Computers in ___. A. Sozialkunde B. Englisch C. Informatik <<<< D. Integralrechnung
May 24, 2016

chemistry
calculate the ph of a solution that is 0.111 M HCI(strong solution)
May 4, 2016

Science
Please chrck my answer! How does a galvanometer use a magnetic field to indicate the strength of an electric current? When a current is passed through a magnetic field, it goes through a coil and to a galvanometer.
April 29, 2016

Math
A square is cut in half on the diagonal, creating two equal triangles.each triangle has an area of 0.32 square units. What is the lenth, in units, of the original square. HELP ME PLEASEE
April 17, 2016

Chemistry
If a rate of 80.0 mL of an aqueous solution of potassium hydroxide concentration of 0.25 mol / L are partially neutralized by 20.0 mL of an aqueous solution of nitric acid concentration of 0.50 mol L. Determine pH of the final solution. kOH + HNO3 -> H2O + KNO3
January 20, 2016

Chemistry
al(i) Determine the number of moles of Ca2+ present in the titrated sample. (ii) Determine the [Ca2+] and hence the solubility of CaSO4.2H2O in the original 10.0 mL sample. so
November 17, 2015

Chemistry
A 10.0 mL sample of supernatant liquid from the system described by equation 1 was titrated with 0.01022 M EDTA solution to an end-point at 16.90 mL. Titration of the blank gave a titre (end-point) at 1.45 mL. Determine the titration volume required to titrate the Ca2+ alone.
November 17, 2015

physics
i did and i still don't understand
November 12, 2015

physics
what is heat
November 12, 2015

physics
ive tried google its all confusing
November 12, 2015

physics
what is diffraction? When does it occur? Which waves will defract more when passing through an opening?
November 12, 2015

Chemistry
Thank you for all your help.
November 10, 2015

Chemistry
The mass of the compound is 0.0218g and if I calculate the mass of Fe I get a mass of 0.31g which is more than the mass of the whole compound.
November 10, 2015

Chemistry
DRBob222 what do you mean when you say That is done by 0.218 x (atomic [mass Fe/molar mass Fe(NH4)2(SO4)2.6H2O]*100 = ? Could you please explain further?
November 10, 2015

Chemistry
The molar mass of the reagent, Fe(NH4)2(SO4)2.6H2O is 392.14 g/mol. Now suppose the measured mass of Fe(NH4)2(SO4)2.6H2O during the practical was 0.0218 g and this was dissolved in 50ml of deionized water that contains 1 to 2ml of concentrated sulphuric acid and transfer ...
November 10, 2015

chemistry
Use the following information to find Hf of butanol [C4H9OH(l)]. C4H9OH(l) + 6 O2(g) 4 CO2(g) + 5 H2O(g) Hcomb = -2712.9 Hf of CO2(g) = -393.5 kJ/mol Hf of H2O(g) = -241.8 kJ/mo
October 23, 2015

chemistry
Calculate H0rxn for each of the following using data from Appendix B. (a) 2 H2S(g) + 3 O2(g) 2 SO2(g) + 2 H2O(g) b) CH4(g) + Cl2(g) CCl4(l) + HCl(g) [unbalanced]
October 23, 2015

chemistry
Calculate Hrxn for the reaction below. 2 NOCl(g) N2(g) + O2(g) + Cl2(g) You are given the following set of reactions. 1/2 N2(g) + 1/2 O2(g) NO(g) H = 90.30 kJ NO(g) + 1/2 Cl2(g) NOCl(g) H = -38.6 kJ
October 23, 2015

chemistry
Organic hydrogenation reactions, in which H2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. In the simplest case, ethene (C2H4) and H2 form ethane (C2H6). If 132 kJ is given off per mole of C2H4 reacting, how much ...
October 23, 2015

chemistry
A mercury mirror forms inside a test tube by the thermal decomposition of mercury(II) oxide. 2 HgO(s) 2 Hg(l) + O2(g) Hrxn = 181.6 kJ (a) How much heat is needed to decompose 556 g of the oxide? (b) If 288 kJ of heat is absorbed, how many grams of mercury form?
October 23, 2015

chemistry
A 30.5 g sample of an alloy at 94.8°C is placed into 52.1 g water at 22.8°C in an insulated coffee cup. The heat capacity of the coffee cup (without the water) is 9.2 J/K. If the final temperature of the system is 31.1°C, what is the specific heat capacity of the ...
October 23, 2015

chemistry
One piece of copper jewelry at 104°C has exactly twice the mass of another piece, which is at 43.0°C. Both pieces are placed inside a calorimeter whose heat capacity is negligible. What is the final temperature inside the calorimeter (c of copper = 0.387 J/gK)?
October 23, 2015

chemestry
What is the enthalpy change when 24.0 g of water is cooled from 40.0°C to 5.70°C? _________kJIs the process endothermic or exothermic?
October 23, 2015

chemestry
27.2 g sample of ethylene glycol, a car radiator coolant, loses 685 J of heat. What was the initial temperature of ethylene glycol if the final temperature is 32.5°C (c of ethylene glycol = 2.42 J/gK)?
October 23, 2015

chemestry
When 36.5 mL of 0.605 M H2SO4 is added to 36.5 mL of 1.21 M KOH in a coffee-cup calorimeter at 23.50°C, the temperature rises to 30.17°C. Calculate H of this reaction per mole of H2SO4 and KOH reacted. (Assume that the total volume is the sum of the individual volumes ...
October 23, 2015

math
convert to fraction: 8.714285714285714285...(the 714285 is repeating.
August 25, 2015

Math
Hey! multiply both the numerator and denominator by the conjugate. in this case it's square root a - square root b.
August 25, 2015

math
rationalize the numerator: ((square root of m)-(square root of 7))/(7-x). thank you so much
August 25, 2015

math help
still don't really quite understand. could you explain your process a bit more?
August 25, 2015

chemistry
Thank You
April 26, 2015

chemistry
methylene blue
April 26, 2015

chemistry
If 5.0 mL of 0.12 mmol dm-3 MB solution is diluted by adding 20.0 mL of 0.2 mol dm-3 HCl to it, what is the new MB concentration?
April 26, 2015

Physics
A certain automobile engine delivers 2.24 ✕ 10^4 W (30.0 hp) to its wheels when moving at a constant speed of 31.0 m/s ( 69 mi/h). What is the resistive force acting on the automobile at that speed?
September 29, 2014

mathes
how do calculate this 55 divided by 3500
April 18, 2014

Earth Science
need help plzz .... I did some but I would like someone to double check them too 1. How did planetesmals form planets? (1 point) A. They broke apart into smaller chunks. B. They collided and stuck together. C. They cooled and pulled ice together. D. They began to rotate. 2. ...
November 8, 2013

English
@Ms.Sue Please check 1.B 2.D 3.A
October 21, 2013

English
is 3 A
October 21, 2013

English
Well then lol could you help me?
October 21, 2013

English
1. Which of the following is not a type of folktale? (1 point) A. cautionary tale B. mystery** C. legend D. myth Read the following sentence: Some friends from my dance class went to the museum's ballet exhibit. Which of the following is an adjectival phrase? A. went to ...
October 21, 2013

Math
i have no idea help
September 3, 2013

What are objects that are between 5 centimeters to 8 centimeters long?
January 20, 2013

Ok were they all right or not very important
December 3, 2012

physics
A shell is ﬁred from the ground with an initial speed of 1.70 × 10 3 m/s (approximately ﬁve times the speed of sound) at an initial angle of 70.0 ◦ to the horizontal. The acceleration of gravity is 9.81 m/s 2 . a) Neglecting air resistance, ﬁnd...
September 18, 2012

physics
A pelican ﬂying along a horizontal path drops a ﬁsh from a height of 3.1 m. The ﬁsh travels 6.4 m horizontally before it hits the water below. What was the pelican’s initial speed? The acceleration of gravity is 9.81 m/s 2 . Answer in units of m/s
September 18, 2012

physics
Janet jumps oﬀ a high diving platform with a horizontal velocity of 1.84 m/s and lands in the water 2.9 s later. How high is the platform? The acceleration of gravity is 9.8 m/s 2 . Answer in units of m
September 13, 2012

math
order 3/10 from least to greastest
September 3, 2012

question
oh ok thankyou
July 24, 2012

question
if you have a chance of 1 out of 60 of your baby having down syndrome is it bad?
July 24, 2012

math
There were 25 students who completed a survey. There were 11 boys and 14 girls. One survey was picked at random. To the nearest hundredth, what is the probability it was completed by a girl?
April 9, 2012

College math
Please, help me with this problem: frind the derivative of each function at the given number. 21. f(x)= -4x + 5 at 3 22. f(x)= -4 + 3x at 1 thanks
October 19, 2011

pompei
what fractions are used for 96 cupcakes
June 10, 2011

algebra rebus puzzle
negative slope
March 27, 2011

pyhsics
I'm actually trying to do this problem right now. I'm a bit stuck on the second part. How do you find the speed of the object at t = 2.0s? Every kinematic equation I've tried to use requires acceleration, and I can't find acceleration with having the final ...
March 15, 2011

lol i need help so you guys are soooo dumb
February 20, 2011

Physics
A watch manufacturer claims that its watches gain or lose no more than 8 seconds in a year. How accurate is this watch, expressed as a percentage?
February 1, 2011

algebra
I need help solving and graphing the equation. y= -7+3
January 27, 2011

physics
a mass 3 kg is dropped from a 20m high stand how long does it take to reach the ground?
January 5, 2011

physics
a mass 3 kg is dropped from a 20m high stand how long does it take to reach the ground?
January 5, 2011

Terrance describes the amount of money made based on the number of hours worked by the function rule y=10h. Given this function, how much money does Terrance earn for each hour worked?
December 1, 2010

the lengths of two sides of a triangle are 15 inches each and the third side measures 10 inches what kind of triangle is that
November 11, 2010

Geometry
Which of the following equals (-4) A(-4) . (1-4) <- That's a fraction B(-4) . (1) C(-4) . (4)
November 8, 2010

How do I answer and graph this problem 4x + 3y = 4
October 27, 2010

English
I have no idea. I haven't seen the animated cartoon of animal farm.
July 30, 2010

English
When an animated cartoon was made of Animal Farm, it was given a happy ending. Animals everywhere hear that Napoleon has betrayed the cause of animalism. They join in a second revolution and succeed in overthrowing him. This leads to the establishment of the original ideal ...
July 30, 2010

english
I surpose you could ask: Why did you become an English teacher? Where did you study to become a teacher? Why did you decide to teach? Is teaching English diffecult? Do you regret you choice to teach? What's your favourite book?
July 30, 2010

History/ Need fast help
What were some of political issues that was dealt in the Gilded age? What is the current political issues that is faced today? Are they Similar or different? Explain.
April 14, 2010

2578 diveded by4
March 1, 2010

U.S. History
To what extent would it be accurate to say that New England, Middle, and Southern Colonies had merged to create a single American Society by the end of the French and Indian War?
September 7, 2009

physics
An electron is accelerated by a 4.7 kV potential difference. How strong a magnetic field must be experienced by the electron if its path is a circle of radius 8.0 cm?
April 15, 2009

physics
A 16.0 ohm and a 24.0 ohm resistor are connected in parallel. A difference in potential of 32.0 V is applied to the combination. What is the equivalent resistance of the parallel circuit? What is the total current in the circuit?
February 25, 2009

physics
A 16.0 ohm and a 24.0 ohm resistor are connected in parallel. A difference in potential of 32.0 V is applied to the combination. What is the equivalent resistance of the parallel circuit? What is the total current in the circuit?
February 25, 2009

Physics
The nucleus of an atom has a charge of 65 protons. (a) What are the direction and magnitude of the electric field at 4.9 x 10^-10 m from the nucleus?
February 8, 2009

physics
d would be 1/4 * F qA and d would be 6 * F
January 27, 2009

physics
Two charges, qA and qB, are separated by a distance, d, and exert a force, F, on each other. Analyze Coulomb's law and answer the following questions. What new force will exist if d is cut in half? What new force will exist if qA is tripled and d is doubled?
January 27, 2009

physics
A positive charge of q = 2.6 µC is pulled on by two negative charges. As shown below, one, −2.0 µC, is 0.050 m to the north and the other, −4.0 µC, is d = 0.029 m to the south. What total force is exerted on the positive charge?
January 22, 2009

physics
Two identical positive charges exert a repulsive force of 6.6 multiplied by 10^-9 N when separated by a distance of 5.8 multiplied by 10^-10 m. Calculate the charge of each.
January 13, 2009

Physics
A student librarian picks up a 2.2 kg book from the floor to a height of 1.10 m. He carries the book 7.9 m to the stacks and places the book on a shelf that is 0.35 m above the floor. How much work does he do on the book?
December 15, 2008

physics
A force of 291.0 N is used to push a 140 kg mass 30.0 m horizontally in 3.00 s. Calculate the power developed in kW.
December 14, 2008

physics
A 0.105-kg hockey puck moving at 20 m/s is caught and held by a 77-kg goalie at rest. With what speed does the goalie slide on the ice?
December 7, 2008

physics
A(n) 840-kg dragster accelerates on a race track from rest to 85 km/h in 0.90 seconds. (a) What is the change in momentum of the dragster? (b) What is the average force exerted on the dragster? (c) What exerts that force?
December 3, 2008

physics
Small rockets are used to make tiny adjustments in the speeds of satellites. One such rocket has a thrust of 35 N. If it is fired to change the velocity of a 72300 kg spacecraft by 64 cm/s, how long should it be fired?
December 1, 2008

Chemistry
CuSo4+BaCl
May 27, 2008

novel
In tale of two cities please answer these questions in chapters 11,12,13: 1-why did darnay decided to go back to paris? 2-"in the name of that sharp female born and called la guillotine why did you come to france" who said these words?to who and when? 3-defarge ...
February 24, 2008

Algebra
Thanks I didn't even think of that! I am however stuck on these problems, i know theres a lot though, any help would be great, but i can't seem to understand the complex numbers, thankyou! Simplify: 1.SquareRoot(-144) 2.SquareRoot(-64x^4) 3.SquareRoot(-13)*SquareRoot(-...
February 8, 2008

Algebra2
Complete parts a – c for each quadratic function: a. Find the y-intercept, the equation of the axis of symmetry and the x- coordinate of the vertex. b. Make a table of values that includes the vertex. c. Use this information to graph the function. 1. f(x) = 2x^2 2. f(x...
February 8, 2008

Algebra2
Simplify: 1.SquareRoot(-144) 2.SquareRoot(-64x^4) 3.SquareRoot(-13)*SquareRoot(-26) 4.(-2i)(-6i)(4i) 5. i^13 6. i3^8 7.(5 – 2i) + (4 + 4i) 8.(3 – 4i) – (1 – 4i) 9.(3 + 4i)(3 – 4i) 10.(6 – 2i)(1 + i) 11. (4i)/(3+i) 12. (10+i)/(4-i) 13. (-5 + 2i)(6...
February 8, 2008

Algebra2
I accidently posted the wrong thing, i will re-post the right assignment for help thankyou!!!
February 8, 2008

Algebra2
Complete parts a – c for each quadratic function. a. Find the y-intercept, the equation of the axis of symmetry and the x-coordinate of the vertex. b. Make a table of values that includes the vertex. c. Use this information to graph the function. 1. f(x) = 2x2 2. f(x) = ...
February 8, 2008

Algebra 2
accidently posted the wrong thing, i will re post the right assignment for help thankyou!!!
February 8, 2008

math
Thank you for the explanation, it will definetly help me with the other problems.
September 23, 2007

math
A rectangle has sides of 3x – 4 and 7x + 10. Find the expression that represents its perimeter.
September 23, 2007

English
"Don't overlook the small things". In other words, without that nail there would be no shoe.
September 23, 2007

Dr.Bob (about finding the ml of ethanol)
Since the solubility of sulfanilamide at 0 C is 14mg/mL, do I multiply 1.5mL and 14 to get how much sulfa will remain in the mother liquor?
September 3, 2007

Dr.Bob (about finding the ml of ethanol)
Using the volume 1.5mL of 95% ethyl alcohol that's required to dissolve 0.3g at 78 C, how do i find how much sulfanilamide that will remain in the mother liquor after the mixture is cooled to 0 C?
September 3, 2007

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