Wednesday
August 27, 2014

Posts by Liz


Total # Posts: 1,149

Chemistry
sorry I forgot to add the rest. I also have the concentration of NaOH which is 1.0 M, pKa is 4.4, and the volume of the acid is 25 mL
August 17, 2014

Chemistry
How would I find the concentration of an unknown acid if I have a Ka value of 3.98x10^-5?
August 17, 2014

calculus
A parallelogram is determined by the vectors a = [-2, 5] and b = [3, 2]. Determine the diagonals of the parallelogram.
August 16, 2014

calculus
Solved
August 16, 2014

calculus
Beth leaves a dock in a motorboat travelling at 14 m/s. She heads downstream at an angle of 40° to the current, which flows at 6 m/s. Determine how long it takes for Beth to travel 400 m
August 16, 2014

SOLVED
SOLVED
August 16, 2014

calculus
For the vectors x=(0,6,-5), y=(2,1,4) and z=(-2,3,-1) what is the value of (2x+y)·(3y-z)? (dot product question and each letter is a vector)
August 16, 2014

calculus
Nikki is driving a motorboat across a river that flows at 5 m/s. The motorboat has a speed of 12 m/s in still water. She heads out from one bank in a direction perpendicular to the current. How far does she travel in 3 minutes?
August 16, 2014

calculus
Determine (6i+2j)· (i-4j+k) This is a dot product question and each letter has the vector symbol
August 16, 2014

Calculus (need help with only d and e)
Codeine phosphate is a drug used as a painkiller. A common brand contains 30 mg of codeine. Samples of blood were taken at regular time intervals from a patient who had taken a pill containing 30 mg of codeine. The amount of codeine in the bloodstream was determined every 30 ...
August 13, 2014

Chemistry
I am given that volume of an unknown acid is 25 mL, volume of NaOH is 13 mL and concentration of NaOH is 1.0 M. I have a graph of a titration curve where the equivalence point is pH=9 (pH on y axis and volume of NaOH on x axis) How would i find the pKa value as well as the Ka ...
August 13, 2014

Chemistry
Ièm studying grade 12 chemistry and this is the Chemical Systems and Equilibrium
August 8, 2014

Chemistry
Thanks but not exactly, the question is asking what would happen if you had more than one product or reactant that was a gas
August 8, 2014

Chemistry
Can you please explain if it would be possible to calculate the K value if more than one product or reactant in a chemical equation is a gas?
August 8, 2014

Chemistry
I am to do an equilibrium constant lab and I am supposed to only find the Kc value. i have to find the equilibrium constant for NaHCO3 (s) <--> NaOH (s) + CO2 (g) at 800K. The partial pressure in the bulb reads 420 kPa on the manometer, 1 gram of NaHCO3 was added to the ...
August 7, 2014

physics
An astronaut in a spaceship is listening to his music. Calculate the time it takes to play a 4.00 minute song at 0.1c
August 4, 2014

physics
I need help with this question. Would you be able to explain it please? Double slit interference patterns exhibit mλ path difference for constructive interference. Single slit diffraction patterns exhibit (m+1/2)λ path difference for constructive interference. With ...
August 4, 2014

physics
Can you please explain how to solve this question? Would I need to use the formula nλ=dsin(theta)? Red light with a wavelength of 660 nm and blue light with a wavelength of 480 nm are beamed at a double slit with a separation of 2x10^-3 mm. The third order maximums for ...
August 2, 2014

Chemistry- practice question
The answer for this question is ΔHrxn=-441.40174468085 kJ/mol but I don't know how to arrive to that answer. 0.47g of magnesium reacts with 100ml of 1.00 mol/L HCl in the following reaction: Mg(s)+2HCl(aq)-->MgCl2(aq)+H2(g). The heat of reaction is -8537.4J ...
August 1, 2014

physics
At exactly the critical angle: a) all light reflects back into the n1 medium b) all light reflects back into the n2 medium c) part of the light reflects back into the n1 medium, the remainder travels along the boundary between the two mediums d) part of the light reflects back...
August 1, 2014

Physics- check answer please
A critical angle of 24.4 degrees applies to: a) light travelling from air into diamond b) light travelling from diamond into air c) light travelling from water into diamond d) light travelling from diamond into water Would the answer be a)?
August 1, 2014

nursing
In what ways does the World Health Organization assist healthcare?
August 1, 2014

physics
At exactly the critical angle: a) all light reflects back into the n1 medium b) all light reflects back into the n2 medium c) part of the light reflects back into the n1 medium, the remainder travels along the boundary between the two mediums d) part of the light reflects back...
July 31, 2014

Physics- check answer please
Would the answer be b)? diamond into air? A critical angle of 24.4 degrees applies to: a) light travelling from air into diamond b) light travelling from diamond into air c) light travelling from water into diamond d) light travelling from diamond into water
July 31, 2014

physics
light travelling in air is incident on a soap bubble. If the path difference through the soap bubble is 2.5λ: a) constructive interference will occur b) destructive interference will occur c) partial interference will occur d) none of the above Would the answer be a?
July 31, 2014

physics
How would I figure out the answer to this question? A critical angle of 24.4 degrees applies to: a) light travelling from air into diamond b) light travelling from diamond into air c) light travelling from water into diamond d) light travelling from diamond into water
July 31, 2014

Physics- check answer please
light travelling in air is incident on a soap bubble. If the path difference through the soap bubble is 2.5λ: a) constructive interference will occur b) destructive interference will occur c) partial interference will occur d) none of the above Would the answer be a?
July 30, 2014

physics
light travelling in air is incident on a soap bubble. If the path difference through the soap bubble is 2.5λ: a) constructive interference will occur b) destructive interference will occur c) partial interference will occur d) none of the above
July 30, 2014

physics
light travelling in air is incident on a soap bubble. If the path difference through the soap bubble is 2.5λ: a) constructive interference will occur b) destructive interference will occur c) partial interference will occur d) none of the above
July 29, 2014

Physics -- check answer please
Light travelling in water is incident on air refracts at an angle of 27 degrees. What is the angle of incidence? my answer: 37 degrees
July 29, 2014

Physics -- check answers please
Light travelling in water is incident on air refracts at an angle of 27 degrees. What is the angle of incidence? my answer: 37 degrees
July 28, 2014

physics
1. If the period of a wave is 0.27s, how many waves would pass by in 1.0 minute? 2. When a wave from of light passes through an opening that's large compared to its wavelength, it: a) behaves as a single new point source b) produces a straight wave front, curved backwards ...
July 28, 2014

Physics -- check answer please
Refraction is: a) the way light behaves when it goes through a narrow opening b)the way teo light sources interact to produce interference patterns c) the absorption of one component of the electric field d) none of the above are correct my answer: d
July 28, 2014

Physics -- check answers please
1. If 31 waves pass by a point in 1.7 s, what's the frequency? my answer: 18.2 Hz 2. if a crest with an amplitude of 7cm interferes with a trough with an amplitude of 10 cm, the resulting wave has an amplitude of: my answer: -3
July 28, 2014

statistics
A researcher wishes to estimate the proportion of adults living in rural areas who own a gun. He wishes to achieve a margin of error of 2.8%. What is the minimum sample size needed?
July 28, 2014

physics
Red light with a wavelength of 660 nm and blue light with a wavelength of 480 nm are beamed at a double slit with a separation of 2x10^-3 mm. The third order maximums for the different colours occur at different spots. What is the angle between the second order maximums?
July 27, 2014

Chemistry
Why would you subtract the heat of a calorimeter when calculating heat of the reaction? hint: the heat of the calorimeter is the amount of heat that the calorimeter absorbs from the solution-each calorimeter will absorb a certain amount of heat, which means that the ...
July 27, 2014

chemistry check answer
Question: Explain whether using solid NaOH pellets rather than aqueous NaOH would alter the enthalpy. If different, would it be higher or lower My answer: Would the result be different since the aqueous NaOH would be able to quickly dissolve in water unlike solid NaOH which ...
July 27, 2014

physics
Fill in blank: Two slits can produce an interference pattern with visible light but this maximal point of constructive interference can be made more pronounced by using many fine lines in a __________
July 27, 2014

physics
Fill in blank Increasing the distance between a pair of slits through which light is being shone would ___ the distance between nodal lines appearing on a screen
July 27, 2014

wavelength
A human's wavelength is similar to the size of: a) a cell b) atom c) nucleus d) proton e) something else and why?
July 26, 2014

Physics
I am to fill in the blanks without a word bank, my answers are in brackets. 1. When light waves reflect from media in which the speed of light is slower, their phase (crest or trough) is ____ 2. The trick to being able to observe interference patterns for light waves in to ...
July 26, 2014

Physics -- check answers please
I am to fill in the blanks without a word bank, my answers are in brackets. 1. A ____ diffraction pattern is unique because it has a larger central maximum. (single slit) 2. the brightest, clearest diffraction pattern is created with a _____ (barrier)
July 26, 2014

Physics
The following figure represents the ride for a cart with a mass of 200 kg along a frictionless track. a. Calculate the velocity of the cart at points A, B, and C if the cart is dropped from a height of 100m with a initial velocity of 10 m/s. b. Calculate the height of the ...
July 25, 2014

Chemistry
I think that the question is saying why you do subtraction in the equation Qrxn=-Qcal-Qsoln
July 22, 2014

Chemistry
Why would you subtract the heat capacity of the calorimeter when calculating the heat of the reaction?
July 22, 2014

Chemistry
For the equation q=cΔt, q=100KJ, initial temp=20 degrees celsius, final temp=31.4 degrees celsius and I need to find c. Do I need to convert the q value from KJ to J?
July 22, 2014

physics
Fill in blank without a word bank (unit is wave nature of light) 1. As water waves travels through a slit barrier, they bend and spread out. This is known as ______ 2. Two identical waves will interfere destructively, cancelling one another out, when one lags behind the other ...
July 21, 2014

Chemistry
For an enthalpy lab, why would calculated value differ from the theoretical value (in percent error) for the heat reaction of Mg/HCl and MgO/HCl
July 21, 2014

SOLVED
I figured out this question
July 21, 2014

Chemistry
Find the enthalpy of combustion of magnesium using Hess' law given the following data (assume that exactly 100.0 mL of HCl was used in each trial and that HCl is in excess) Magnesium/HCl reaction: Grams of Mg= 0.244g Initial temp= 32.2 degrees celsius Final temp= 21.3 ...
July 21, 2014

Chemistry
No, the question only says Mg
July 21, 2014

Chemistry
why can't the enthalpy of magnesium be measured using a coffee cup calorimeter?
July 21, 2014

chemistry
It is ok to have a negative percent error? I got a negative value for the percent error of the enthalpy of the formation of methane gas
July 20, 2014

Chemistry
The combustion reaction of Mg +1/2 O2-->MgO produces a very bright white flame and high heat. Verify that the following reactions produce the same overall reaction: a) MgO+2HCl-->MgCl2+H2O b) Mg+2HCl-->MgCl2+H2 c) H2+1/2O2-->H2O ΔH°= -285.8 KJ/mol
July 20, 2014

Chemistry
I am to use this formula to find ΔH°f,methane: ΔH°comb=2ΔH°f,water+ΔH°f, carbon dioxide-ΔH°f,methane-2ΔH°f,oxygen For ΔH°comb, the value is 884 KJ/mol For ΔH°f,water, the value is -285.8 For ΔH°f,...
July 20, 2014

Chemistry
ok I got it now!
July 20, 2014

Chemistry
Ok thanks! I used PV=nRT to calculate the mols but I got a larger number. Here's what I did: P= 1.000 atm V= 0.271 L R= 0.08206 Latm/molK T= 2.3 K and I got 1.436 as my answer
July 20, 2014

Chemistry
A calorimeter is filled with 10.0 millimole (mmole) of methane gas and an excess of oxygen. When burned, the ignition wire releases 140.77 J of heat. The heat capacity of the calorimeter is 4.319 KJ°C-1. qwire= 140.77 J Calculate ΔHcomb. Recall that ideal gas law is ...
July 20, 2014

Chemistry
Ok I understand it now! Thank you so much!
July 19, 2014

Chemistry
Oh so answer would be 907 J/mol? also for the thermochemical equation you said it would be CH4 + 2O2 ==> CO2 + 2H2O with ΔH=- 890 kJ/mol but I don't know how to calculate that value
July 19, 2014

Chemistry
I have previously posted this question, but now I am lost question: A calorimeter is filled with 10.0 millimole (mmole) of methane gas and an excess of oxygen. When burned, the ignition wire releases 107.2 J of heat. The heat capacity of the calorimeter (including the bomb and...
July 19, 2014

Chemistry
I got 0.907 KJ for ΔHcomb but I don't know if its correct. I also don't know how to write the equation. -------- question: A calorimeter is filled with 10.0 mole of methane gas and an excess of oxygen. When burned, the ignition wire releases 107.2 J of heat. The ...
July 16, 2014

Chemistry
Yes the initial temperature is 24.75 degrees celsius and the final temperature is 26.85 degrees celsius
July 16, 2014

Chemistry
I got 0.907 KJ for ΔHcomb but I don't know if its correct. I also don't know how to write the equation. -------- question: A calorimeter is filled with 10.0 mole of methane gas and an excess of oxygen. When burned, the ignition wire releases 107.2 J of heat. The ...
July 16, 2014

Unified field theory
Einstein sought to discover a unified field theory that would explain the behaviour of all fields. What evidence have you seen to suggest that such a theory exists? Is there anything to suggest that it doesn't?
July 15, 2014

physics
A particle with a charge of -4.0x10^-5 C, a mass of 2.0x10^-7 kg and a velocity of 6.0x10^4 m/s [W] is travelling perpendicularly through an external magnetic field such that the force of gravity is balanced by the magnetic force. Determine the direction and magnitude of the ...
July 15, 2014

physics
A charge with a value of 3.0 x 10^-5 C is located 3.0 cm from a charge with a value of 6.0 x 10^-5 C. Determine the distance from the larger charge to the point where the total electric field is zero
July 15, 2014

chemistry
How would polyethylene have the VSEPR shape of tetrahedral?
July 14, 2014

physics
A particle with a charge of -4.0x10^-5 C, a mass of 2.0x10^-7 kg and a velocity of 6.0x10^4 m/s [W] is travelling perpendicularly through an external magnetic field such that the force of gravity is balanced by the magnetic force. Determine the direction and magnitude of the ...
July 14, 2014

Physics help
A charge with a value of 3.0 x 10^-5 C is located 3.0 cm from a charge with a value of 6.0 x 10^-5 C. Determine the distance from the larger charge to the point where the total electric field is zero
July 14, 2014

Physics help
A particle with a charge of -4.0x10^-5 C, a mass of 2.0x10^-7 kg and a velocity of 6.0x10^4 m/s [W] is travelling perpendicularly through an external magnetic field such that the force of gravity is balanced by the magnetic force. Determine the direction and magnitude of the ...
July 14, 2014

physics
A charge with a value of 3.0 x 10^-5 C is located 3.0 cm from a charge with a value of 6.0 x 10^-5 C. Determine the distance from the larger charge to the point where the total electric field is zero
July 13, 2014

physics
A particle with a charge of -4.0x10^-5 C, a mass of 2.0x10^-7 kg and a velocity of 6.0x10^4 m/s [W] is travelling perpendicularly through an external magnetic field such that the force of gravity is balanced by the magnetic force. Determine the direction and magnitude of the ...
July 13, 2014

physics
A 1000 kg rocket without an internal propulsion system is launched with an initial speed of 7.00 x 10^2 m/s. Determine the maximum height attained by the rocket
July 13, 2014

physics
1. which of the following is not true about magnetic field lines a) mag. field lines flow from North to South inside the magnet b) mag. field lines do not cross c) mag. field line density is proportional to field strength d) mag. field is strongest closest to the ends of a bar...
July 12, 2014

physics
Would the answer be c? The electrical potential 10 cm from an electron is: a) 1.4x10^-8 V b) 1.4x10^-10 V c) 1.4x10^-7 V d) 1.2x10^-4 V
July 12, 2014

physics
Would the answer be a? Which two forces balanced in the Millikan oil drop experiment a) electric and gravitational b) electric and magnetic c) magnetic and gravitational d) none of the above
July 12, 2014

physics
thanks! and thanks for the link, its quite useful!
July 12, 2014

physics
The escape velocity on the moon is: a) 5.64x10^6 m/s b) 1.68x10^3 c) 160 m/s d) 2.38x10^3 m/s
July 12, 2014

physics
thanks!
July 12, 2014

physics
If the electric field near a proton is 9.00 x 10^-3 N/C, what is the distance from the proton?
July 12, 2014

chemistry
explain whether using solid sodium hydroxide pellets rather than aqueous sodium hydroxide would alter the enthalpy
July 11, 2014

chemistry
Why would you have to subtract the heat capacity of the calorimeter when calculating the heat of the reaction?
July 11, 2014

chemistry
Why would you have to subtract the heat capacity of the calorimeter when calculating the heat of the reaction?
July 11, 2014

Physics
all electric field lines start on positive charges. explain why this makes sense.
July 10, 2014

physics
What is a charge dipole a basic model of? would it be a magnet?
July 10, 2014

Physics- help please
A beta particle (fast moving electron) is released by a nuclear decay and starts travelling at 1.5x10^6 m/s [NΘE] in the Earth's magnetic field which has a value of 3.0x10^-5 T. If the force experienced by the beta particle is 4.34x10^-18 N, determine the angle ...
July 10, 2014

Physics
Two parallel wires are carrying current. If the currents are in the same direction, what is the interaction between the two wires and why? How would this be different in the currents were in opposite directions?
July 9, 2014

Physics help
1. if the magnetic field is 2.1 m from a current carrying wire is 7.1x10^-5 T, what is the current flowing through the wire? 2. The electromagnet in an MRI has a magnetic field of 2.5 T. If there are 100 A of current running through the magnet, how many turns are there in a 1....
July 9, 2014

Physics
1. You are looking into a current carrying solenoid and notice that the compass needle indicates that you are at the south end of the magnetic field. What is the direction of the current in the coil and how do you know? Would it be clockwise because current moves towards the ...
July 8, 2014

Physics- check answer please
1. A 15 kg boy falls out of his bed at a height of 0.50 m. What is the amount of gravitational potential energy lost by the boy? my answer: 74 J 2. What is the speed of a 0.25 kg ball if its kinetic energy is 15 J? my answer: 11 m/s 3. if the speed of an object is tripled and ...
July 4, 2014

Physics
a child throws a ball in a net where it gets stuck. Does the motion of this ball defy the law of conservation of momentum? explain
July 4, 2014

physics word problem
A 60.0 kg girl stands up on a stationary floating raft and decides to go into shore. She dives off the 180 kg floating raft with a velocity of 4.0 m/s [W]. Ignore the substantial friction real objects in water experience. What is the speed of the raft just after the girl dives?
July 4, 2014

physics
How would I answer number 3? 1. A sumo wrestler originally jumps 10 cm above a trampoline but has the same total energy of a small ball that was 200 cm higher than the trampoline. What causes this equivalency? 2. If a 40 kg gymnast and a 400 kg sumo wrestler each dropped from ...
July 3, 2014

Physics
A sumo wrestler originally jumps 10 cm above a trampoline but has the same total energy of a small ball that was 200 cm higher than the trampoline. What causes this equivalency?
July 3, 2014

Physics -- check answers please
Use g=10 N/kg in this assignment. 1. What is the gravitational energy (relative to the unstretched surface of the trampoline) of the 20 kg ball at its apex 2 m above the trampoline? I got 400 J 2. What is the kinetic energy of the ball just before impacting the trampoline? I ...
July 3, 2014

Check answers please?
Use g=10 N/kg in this assignment. 1. What is the gravitational energy (relative to the unstretched surface of the trampoline) of the 20 kg ball at its apex 2 m above the trampoline? I got 400 J 2. What is the kinetic energy of the ball just before impacting the trampoline? I ...
July 3, 2014

Physics
fill in the blank ( Energy and momentum unit) 1. the work done to stretch a spring is not equal to the to force multiplied by displacement because force is ____ as the spring stretches 2. A child goes down a slide at the playground, gaining speed as she goes. Her momentum ____...
July 3, 2014

Physics- check answer please
I am supposed to fill in the blanks without a word bank. 1. I you push a crate with 40 N of force at an angle of 30 degrees and your friend pushes with a force of 40 N horizontally, the amount of work you are doing is _____ the amount of work your friend is doing on the crate ...
July 2, 2014

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