Thursday

July 28, 2016
Number of results: 59,768

**Chemistry**

When solving Hess law problems,do we need to use all the equations given to get the Htotal or just choose the relevant equations that are related to the final equation required? Let's say there r 5 equations given,but the relevant equations are 3 only ,so we can neglect the ...
*March 23, 2012 by Meenaakshi*

**Chemistry**

What are the equations for these two equations? Not net ionic equations. a) Nickel (II) chloride and iron b) Sodium and water
*October 12, 2013 by Matt*

**Chemistry**

COMPLETION AND BALANCING OF EQUATIONS Complete and balance the following equations: 1. ZnCl2 + AgNO3
*March 7, 2007 by Muhammad Ahsan KHan*

**Chemistry**

COMPLETION AND BALANCING OF EQUATIONS Complete and balance the following equations: 1. ZnCl2 + AgNO3
*March 7, 2007 by Muhammad Ahsan KHan*

**Chemistry**

Balancing chemistry equations and need help! Thank You!? Help balancing any of the following equations: Cl2+Na Br----> NaCl2 + Br Na+LiOH---->
*October 13, 2011 by Ginger*

**Chemistry**

Write balanced equations for the formation of K4[Ni(NCS)6] starting from an anhydrous sample of nickel(II) nitrate. (3 equations necessary)
*March 11, 2009 by Alice*

**Math 116**

Consider the following system of equations. y=2x-2 y-2x=9 What can you conclude about the system of equations? a. The system of equations is inconsistent. b. The system of equations is dependent. c. The system of equations is independent. d. none of these.
*June 21, 2013 by Queta*

**chemistry**

complete and balance the following molecular equations and then write net ionic equations for each reaction. BaCl2(aq) + K2SO4(aq) KNO3(aq) + HCl(aq)
*June 21, 2011 by chelsea*

**Math 1**

Consider the following system of equations. y = 4x - 4 y - 4x = 3 What can you conclude about the system of equations? A) The system of equations is inconsistent. B) The system of equations is dependent. C) The system of equations is independent. D) none of these
*October 20, 2013 by sam*

**math**

Consider the following system of equations. y = 2x - 2 y - 2x = 7 What can you conclude about the system of equations? The system of equations is inconsistent. The system of equations is dependent. The system of equations is independent. none of these
*September 8, 2014 by robert*

**Chemistry**

Does anyone know of any sites that make learning to balance equations easy? I just transferred to a new school and the chemistry class is way ahead of my old class. I really don't get it. Please help since there is a test tomorrow and it's on stuff that you have to be able to ...
*February 12, 2008 by Jessica*

**Chemistry**

I understand how to balance equations when the full equations are given to me but I don't understand how to write a single replacement reaction. Help Me??
*January 24, 2011 by Jessica*

**chemistry**

How to balance a chemical equations quickly? please tell me a shortcut to balance any type of equations.
*September 23, 2012 by J.Nandhini*

**chemistry**

Metals + cold water. Li, Na, K, Ca. Notes on reactions, equations or space? <<<< dont no what space or equations means. can someone help? Also, say order of reactivity.
*March 14, 2009 by Nabiha*

**Chemistry**

Write the word equations below as chemical equations and balance. copper + sulfuric acid yield copper(II) sulfate+ water + sulfur dioxide
*December 1, 2010 by Pedro*

**Chemistry**

Question: write the balanced equations for the titration of oxalic acid (C2H2O4) with KOH. Work so far: I know that the overall equation is COOH)2 + 2KOH ------.> (COOK)2 + 2H2O but I am unsure how to proceed to the two step-wise equations
*April 9, 2016 by Alexa*

**Chemistry**

Mg(s) + 2HCl(aq) -> MgCl2(aq) + H2(g) delta H1? MgO(s) + 2HCl(aq) ->MgCl2(aq) + H2O(l) delta H2? To make these equations add up to the formation reaction of MgO, you will need to include the following: H2(g) + 1/2O2(l) delta H =-241.8 kJ Using Hess's Law and manipulating...
*February 14, 2012 by Hannah*

**math**

Explain why the simultaneous equations y=1/2x+2 and 2y-x:4 have an infinite number of solutions. What is diffrent about these equations compared with the equations in the first question ( the equations were y=2x+3 and 5y-10x=5)? What is similar? ( include work to prove why and...
*February 24, 2011 by CJ*

**math**

Consider the following system of equations. Y = 3x – 7 Y - 3x = 5 a) The system of equations is inconsistent. b) The system of equations is dependent. c) The system of equations is independent. d) none of these
*January 27, 2013 by monet*

**Algebra**

Translate to a system of equations. DO NOT SOLVE. A nontoxic scouring powder is made up of 4 parts baking soda and 1 part vinegar. How much of each ingredient is needed for a 16-oz mixture? What are the two equations? For most problems, I can easily find the info for the two ...
*February 19, 2009 by Tessa*

**Chemistry**

Write formula equations and net ionic equations for the hydrolysis of the following salts in water. a. sodium carbonate b. ammonium bromide I don't know what the products should be. a. Na2CO3+H2O--> ? b. NH4Br+H2O--> ? Please help me with this. I really need this. Thanks...
*April 24, 2009 by anonymous*

**chemistry**

how do you do ionic equations Do you mean net ionic equations?
*October 23, 2006 by sarah*

**Math, Year 10, Simult. Equations**

How can i know if two lines/equations intersect on a graph, algebraically? For example, I have two equations: 1. -x^2 + 3x + 4, and 2. x - 4 Ty in advan.
*June 8, 2016 by Anonymous*

**math**

solve the simultaneous equations to find the coordinates of the point of intersection for the pair of lines of the simultaneous equations. Then check the answer by graphing the equations 3x-y=-4 2x-y=0
*October 16, 2010 by Lauren*

**Algebra 2**

1.) Write a system of equations that has NO solution. 2.) If you wanted to eliminate the y variables in the system of equations below, what would you multiply the first and second equations by?( Do not solve the equation) 2x-3y=8 7x-4y=11
*October 3, 2007 by Audrey*

**Algebra 2**

1.) Write a system of equations that has NO solution. 2.) If you wanted to eliminate the y variables in the system of equations below, what would you multiply the first and second equations by?( Do not solve the equation) 2x-3y=8 7x-4y=11
*October 4, 2007 by Audrey*

**Algebra 2**

1.) Write a system of equations that has NO solution. 2.) If you wanted to eliminate the y variables in the system of equations below, what would you multiply the first and second equations by?( Do not solve the equation) 2x-3y=8 7x-4y=11
*October 5, 2007 by Audrey*

**Chemistry**

I am learning the different types of chemical reactions synthesis, decomposition, single displacement, and double displacement I am also learning skeletal equations word equations and balancing the equations I know how to balance equations if I am given the formula in symbols ...
*March 3, 2014 by Sam*

**CHemistry **

Redox equations are often long and difficult to balance by inspection. Luckily, electron transfers and oxidation numbers provide hints for balancing such equations. Balance the following equation: K2CrO4 + Na2SO3 + HCl ---> KCl + Na2SO4 + CrCl3 + H20
*April 13, 2010 by Katelynn*

**Chemistry**

Write balanced equations for the formation of [Ni(NH3)6][BF4]2 starting from an anhydrous sample of nickel(II) choride hexahydrate. (3 equations necessary) I am slightly confused by this. I think the starting sample has the formula [Ni(H20)6]Cl2 Would this react with ammonia...
*March 11, 2009 by Alice*

**math**

How do you solve system of equations and tell if they're consistant and independant,consistant and dependent,and inconsistant? If you find no solutions then the system is inconsistent. Suppose you have N variables and M equations (N larger than or equal to M). Then, if you ...
*July 27, 2007 by maddie*

**Chemistry-Repost**

Write formula equations and net ionic equations for the hydrolysis of sodium carbonate in water. Responses Chemistry - DrBob222, Friday, April 24, 2009 at 10:50pm The hydrolysis of Na2CO3 ends us as the hydrolysis of the carbonate ion. The molecular formula is Na2CO3 + HOH==...
*April 25, 2009 by anonymous*

**Math**

Stupid question time. I need to figure out how to rearrange equations to solve for x in my chemistry homework, which involves putting equations in quadratic form first. But I can't for the life of me remember how to "rearrange" them correctly. So what in the step by step way ...
*March 4, 2013 by Marcus *

**math**

please anwer these: 1) how can i multiply and divide polynomials containing radicals? 2) how can i solve radical equations? 3) how can i solve qudratic equations by factoring ? 4) how can i solve quadratic equations graphically ? thank you !!!!!
*August 13, 2014 by chen*

**Chemistry-Balancing Equations**

I need help balancing equations. _C7H60+_02->_C02+_H20 I don't know how to balance it because when i do it just won't work out ill have too much on one side and it just wouldn't work. i know im missing a rule or something.
*January 12, 2010 by Jason*

**algebra**

solve the system of equations by graphing. Then classify the system as consistent or inconsistent and the equations as dependent or independent. x+y=14 x-y=2 What is the solution of the system of equations?
*March 23, 2008 by anaya*

**alegebra**

solve the system of equations by graphing. then classify the system as consistent or inconsistent and the equations as dependent or independent. 3u+v=13 3u=v+29 What is the solution of the system of equations?
*March 23, 2008 by anaya*

**chemistry**

Write the rate equation for the relative disappearance of dinitrogen pentoxide. Write the rate equations for the relative appearance of nitrogen dioxide and oxygen gas. When writing the equations, remember to think about how many NO2 and O2 molecules are formed from 2 N2O5.
*April 26, 2012 by Anonymous*

**chemistry- redox**

Complete and balance the following equations using the method of half-reaction. both reactions happen in acidic solutions: a. Cu(s) + NO3-(aq)--> Cu2+(aq) + NO2(aq) b. Mn2+(aQ) + NaBiO3(s)--> Bi3+(aq) + MnO4-(aq) I'm having trouble getting the half-rxn equations and the ...
*September 12, 2010 by lucylu*

**chemistry**

Net Ionic equations for.. 1. Co(NO3)2 + NH3 --> ?? 2. Cu(NO3)2 + NH3 --> ?? 3. Ni(NO3)2 + NH3 --> ?? I can balance equations, I just don't know what goes on the products side.
*July 15, 2009 by paul*

**chemistry**

Which of the following equations represents a reaction for which the delta H can be called a standard enthalpy of formation, delta Hf? a) FeO(s) + CO2(g) -> FeCO3(s) b) 1/2 N2(g) + 2 O(g) -> NO2(g) c) 2 Na(s) + Cl2(g) -> 2 NaCl(s) d) Ba(s) + N2(g) + 3 O2(g) -> Ba(...
*January 23, 2012 by timmy*

**CHEMISTRY HELP ASAP!**

is it possible for one molecule of salicylic acid to form an ester with a second molecule of the same substance? Use equations and/or structures. Please help, i am pretty sure it couldn't because of steric hindrance, however i am not sure how to explain this further and what ...
*September 11, 2012 by joel*

**Math**

How do I write the Symmetric Equation of a line given the following parametric equations: (where t is a scalar) x=0t y=0t z=1+1t I know normally I would solve each equation for t and set the equations equal to one another. However, I can not solve for t in the first two ...
*November 3, 2010 by Dwight*

**Math**

How do I write the Symmetric Equation of a line given the following parametric equations: (where t is a scalar) x=0t y=0t z=1+1t I know normally I would solve each equation for t and set the equations equal to one another. However, I can not solve for t in the first two ...
*November 4, 2010 by Dwight*

**Chemistry- gaz and stoechiometry **

The preparation of KClO3 follows these equations: 2KMnO4 + 16HCl->2KCl + 2MnCl2 + 5Cl2 (g) + 8H2O 3Cl2 (g) + 6KOH ->KClO3 + 5KCl + 3H2O 1) How many moles of KClO3 are produced by one mole of KMnO4 I think the only link between the two equations is Cl2 but I don't ...
*April 28, 2016 by Ele*

**College Algebra**

Solve the system of equations with ROWOPS program. I know how to do the first step but after that it gets difficult for me, this is the system of equations: 3x + y - z = 1 x + 2y - z = 0 2x - y + z = 4 I used to be able to do these but now I'm getting a little rusty. Thanks ...
*August 2, 2007 by Rebecca*

**chemistry (need asap!)**

is it possible for one molecule of salicylic acid to form an ester with a second molecule of the same substance? Use equations and/or structures. Please help, i am pretty sure it couldn't because of steric hindrance, however i am not sure how to explain this further and what ...
*September 11, 2012 by joel*

**Predicting products for electrolysis**

when you have your 4 different equations to form 4 different possible equations, what two equations do you use for water, O2(aq) + 4H+ + 4e- ----> 2H20 (+1.23) 02 (g) + 2H2O (l) + 4e- ----> 4OH- (+0.40) 2H20 (l) + 2e- ---> h2 (g) + 2OH- (aq) (-0.83) I'm not quite sure...
*January 16, 2007 by Sienna*

**chemistry**

use thermochemical equations shown below to determine enthalpy for the reaction: H2CO3-->H2O+CO2 1) H2CO3 --> H2CO + O2 H; 224 KJ 2)H2CO + O2 --> H2O + CO2 H; -100KJ I know this problem is one that you have to rewrite the equations to get the equation in the original ...
*November 20, 2009 by Brittany*

**chemistry**

use thermochemical equations shown below to determine enthalpy for the reaction: H2CO3-->H2O+CO2 1) H2CO3 --> H2CO + O2 H; 224 KJ 2)H2CO + O2 --> H2O + CO2 H; -100KJ I know this problem is one that you have to rewrite the equations to get the equation in the original ...
*November 20, 2009 by Brittany*

**Math: Parametric Equations**

Let G be the graph of the parametric equations x = cos(4t), y = sin(6t). What is the length of the smallest interval P such that the graph of these equations for all t E P produces the entire graph G? (The "E" represents the symbol for "is in" that looks kind of like a rounded E)
*April 9, 2016 by Katie*

**engineering**

Using mechanics of materials principles, (i.e. equations of mechanical equilibrium applied to a free-body diagram), derive the following equations: s’ = s cos2q = s[(1+ cos 2q) / 2] t' = s sinq cosq = s [sin 2q / 2] s=sigma, q=theta, t=tau I have looked in "Theory of ...
*October 18, 2010 by Bob*

**Math - system of equations**

write two other equations that have the same solution as this system od equations. 3x-4y=-14 -x+3y=18 I found the solution to the system it is (6,8) there after how do i go about it?
*September 7, 2010 by Shaila*

**Physical Chemistry**

In my physical chemistry book, I'm reading about "Margules Equations": ln γA = ΒxB2 ln γB = ΒxA2 I don't understand where these equations come from. How is it known that there is a single constant Β that satisfies both relationships?
*May 5, 2009 by Sean*

**Chemistry**

The two most common oxidation states are Cr(III) and Cr(VI). Balance the following oxidation-reduction equations that involve one of these oxidation states of chromium. Assume that the reactions occur in acidic solution. A. Cr(s) + O2 (g) + H^+ <-> Cr^3+ B. Fe^2+ (aq) + ...
*February 24, 2016 by Anonymous*

**Chemistry URGENT PLEASE PLEASE PLEASE HELP! **

Determine whether the solution is basic, acidic, or neutral. Write net ionic equations to show how it behaves in aqueous solutions. 1) Fe2(SO4)3 I know it is acidic Do I do hydrolysis equations for the net ionic or do I do redox reactions?
*November 5, 2015 by Anonymous *

**algebra 1**

I'm stuck on this problem. Can you help? -4x-9y=1 -x + 2y =-4 WHat is x and y? Two equations in two unknowns. Here is a quick way to solve them -4x - 9y = 1 4x - 8y = 16 (I got that my multiplying both side so the secind equation that you provided by -4) Now add the two ...
*December 5, 2006 by kyle*

**Math **

Solve the following system of equations by graphing. If the system is inconsistent or the equations are dependent, say so 5x-2y=3 10x-4y=6 I know the equations are dependent but I am confused on what is the solution set I'm thinking its (10x-4y=6) but I'm really not sure.
*November 22, 2015 by Lataya *

**Chemistry**

Why doesn't potassium ion K+ from KMnO4 appear in the following two unbalanced equations: MnO4– + C2O42– Mn2+ + CO2 MnO4– + Fe2+ Mn2+ + Fe3+ ? The potassium ion is a spectator ion. You have written ionic equations (but omitted the arrows to separate the reactants from the ...
*April 29, 2007 by Emi*

**alegebra**

Solve the system of equations by graphing. Then classift the system as consistent or inconsistent and the equations as dependent or independent. 3x-y=14 3x+4y=-26 What is the solution of the system of equations? Type an ordered pair.N for no solution R for the solution if real...
*March 23, 2008 by anaya*

**chemistry**

our lab experiment was Isolationa nd Identification of the Major Constituent of Clove Oil. We know the major component is Eugenol, but our professor wants us to write the equations for the extraction of eugenol from the distillate with dichloromethane and then the equation for...
*April 20, 2011 by pamela*

**Math**

Write two equations that have your two integers as solutions. Show how you built the equations using your integers, numbers used 5 and 8. Solve your system of equations by the addition/subtraction method. Make sure you show the necessary 5 steps.
*September 28, 2011 by Klint*

**Math**

I am stuck on trying to figure out how to do this question. Could someone please show me 5 necessary steps ? Thank you. Here is how the assignment question is worded. Select any two integers between -12 and +12 which will become solutions to a system of two equations. Write ...
*February 9, 2011 by Tiffany*

**Chemistry**

I'm having alot of trouble in chemistry. Currently were studying chemical equations and reactions. I would like to know if this is a single or double replacement reaction. 2Li + H2O ---> 2LiOH + H2
*March 13, 2009 by Alexandria*

**chemistry**

Why does a titrated sample that is fuschia with phenolphthalein turn colorless when the solution is blown into? HINT: Use chemistry and properly balanced chemical equations to support your statement.
*May 13, 2015 by Nicole*

**Algebra **

To solve the following system of equations by elimination, which step would best to perform first? 1/2a - 1/4b = 1 1/3a + b= 3 A. Add the two equations. B. Subtract the two equations. C. Multiply the first equation by 4. D. Divide the first equation by 3.
*December 17, 2014 by Anonymous*

**Chemistry**

Need for two balanced chemical equations? I am in need of these two equations which I however do not know how they react. If anyone could help, it is greatly appreciated :) "Formation of products by heating a solid mixture of calcium propanoate and soda lime" "Formation of a ...
*January 29, 2013 by Matt*

**chemistry**

how do you balance equations?
*January 25, 2009 by ashley*

**math**

how do i solve two step equations? Do you mean two equations in two unknowns? The method of substitution is one way. There is a good tutorial here: http://www.themathpage.com/alg/simultaneous-equations.htm
*January 18, 2007 by megan*

**quantitative chemistry **

Determine [Zn2 ], [CN–], and [HCN] in a saturated solution of Zn(CN)2 with a fixed pH of 1.78. The Ksp for Zn(CN)2 is 3.0 × 10–16. The Ka for HCN is 6.2 × 10–10. I know the following is what needs to be done, but im unsure of how to go about it. 1. Write the pertinent ...
*March 22, 2013 by Jackie*

**Chemistry**

This is for grade 11 chemistry, balancing equations. Help asap? I'd like to get it done by tonight, if possible. Type of reaction: Predict product in words: Write Balance equation: Heres the question. Aluminum+ Zinc Sulfide =
*March 13, 2016 by Colton*

**Trig**

How do you convert rectangular equations into polar equations? If x4−y4=xy , then r2=atan(b); What is a? What is b?
*December 13, 2010 by Audrey*

**Math 8R - HELP!**

Multi-Step Equations Systems of Equations x + y = 0 5x + 2y = -3 this is what i got so far.... x + y = 0 ----> x = 0 - y 5x + 2y(0-y) = -3 please help!!!!
*January 31, 2013 by Lauren *

**PLEASE HELP WITH DIFFERENTIAL EQUATIONS QUESTION??**

Which of these equations have an equilibrium solution. What are they? How are their DE's different? dy/dx=6y-y^2 dy/dx 15-3y
*December 3, 2014 by Francine*

**Chemistry**

2)Which of the following equations represents a reaction for which the delta H can be called a standard enthalpy of formation, delta Hf? a) FeO(s) + CO2(g) -> FeCO3(s) b) 1/2 N2(g) + 2 O(g) -> NO2(g) c) 2 Na(s) + Cl2(g) -> 2 NaCl(s) d) Ba(s) + N2(g) + 3 O2(g) -> Ba...
*January 21, 2012 by Hannah*

**biology**

I need help figuring out how to balance scientific equations well what are the equations?
*October 30, 2006 by ccw*

**Vectors**

How to solve a system of equations if there are FOUR equations with THREE unknowns?
*August 28, 2013 by vectors123*

**Math - Equations**

Just learned equations and want to know if i am doing write.. 4y= 2x-2 2y=2x6 ans (-7,-4) x+2y=7 3x-2y= -11
*March 15, 2015 by Marie*

**chemistry**

how to balance chemical equations
*November 20, 2010 by Linda*

**Chemistry**

how do you balance equations to get the formula?
*October 11, 2012 by Help*

**Math**

Find parametric equations and symmetric equations for the line of intersection of the given planes. x + y + z = 2, x + z = 0 X=1 y = Z= x=, y=
*April 13, 2010 by Mike*

**algebra 2**

Solve system of equations.Describe each step if your solution. W+X+Y+Z=2 2W-X+2y-Z=1 -W+2x-y+2z=-2 3w+x+y-Z=5 Please help I only know how to do this with 3 equations.
*October 16, 2013 by erick*

**Math**

How would I expand this two quadratic equations and find a & x for both of them? Here are my equations: y=a(x+1.5)^2+0 y=a(x+2)^2+1.5
*November 28, 2014 by Alex*

**Mathematics**

Q 1 . Change the following polar equations into Cartesian equations: (a) r = a sin 2 A (b) A=π/4
*January 10, 2016 by Naushad K*

**Maths**

Change the following polar equations into Cartesian equations: (a) r = a sin 2 A (b) A=π/4
*January 11, 2016 by Naushad K*

**Math: Parametric Equations**

The graph of the parametric equations x=cos(t) y=sin(t) meets the graph of the parametric equations x=2+4cos(s) y=3+4sin(s) at two points. Find the slope of the line between these two points. So far I've set up the system of equations cos(t)=2+4cos(s) sin(t)=3+4sin(s) but it ...
*April 10, 2016 by Katie*

**Algebra Quadratic Equations**

What are the pros and cons of completing the square as a way to solve quadradic equations?
*February 15, 2008 by Marysvoice*

**Math**

Which of the following equations gives the relationship between S and T in the table below? S 1 2 3 4 5 6 T 1 4 7 10 13 16 How do you find equations again?
*June 3, 2015 by Anna*

**Math 8 HELP!**

Multi-Step Equations Systems of Equations y = 2x - 4 y = x - 1 please help!!! :'(
*January 30, 2013 by Laruen *

**algebra 2**

How does writing equivalent equations help you solve a system of equations?
*September 25, 2015 by cj*

**Math**

My math teacher said to use the FOIL (First Outer Inner Last) property to simplify these quadratic equations I have made from looking at two parabolas. Here are my equations & how would you use the FOIL property on each of the equations and also can someone help me with ...
*December 4, 2014 by Alex*

**AP Chemistry**

What is meant by minimum and maximum energy problems. Are there different equations to find them. What does this conceptually mean? * This is dealing with quantum chemistry such as plancks equation, and debroglie equation.
*November 18, 2010 by qwerty123*

**quick question regarding equations**

I know there are methods out there but what do you think is the best or easiest method(s) of solving a system of equations. Depends on the coefficients of the equation. If in one of the equations I can solve for one of the variables without having to express it in fractions, I...
*August 14, 2007 by Shawn*

**math,correction**

I have to determine which two equations represent parallel lines. equations are (a) y=(-4)x+2 (b) y=(4)x+2 (c) y= (1/2)x +2 (d) y=(-4)x+3 so the answer would be: A and D yes
*January 28, 2007 by Jasmine20*

**Math**

I have figured out x to be 2 for this system of equations but now I need help on determining the solution of the equations which are y=4x and y=2x^2. Can you please help me!
*January 15, 2015 by Alex*

**math**

1. Select any two integers between -12 and +12 which will become solutions to a system of two equations. 2. Write two equations that have your two integers as solutions. Show how you built the equations using your integers. Your solution and equations should not be the same ...
*March 31, 2011 by John*

**chemistry**

Titration of Vitamin C tablets Prior to titration, Vitamin C samples were dissolved in dilute sulfuric acid, treated with a 60mL portion of 0.3 M KIO3 and excess KI. Given equations: (1) ascorbic acid + I2 + 2H2O <--> dehydroascorbic acid + 2I^- + 2H3O^+ (2) IO3^- + 5I...
*November 23, 2009 by mimi--PLEASE HELP VERY CONFUSED*

**chemistry**

i have aproblem in balancing equations
*July 6, 2011 by nidhi*

**Chemistry**

Describe what hard water is and how a water softening unit works. Provide balanced chemical equations to show how sodium sulphate can remove these ions (Magnesium and Calcium). The first was no problem, but I am having trouble trying to get through the second part balancing ...
*July 17, 2012 by Hannah*

**Vectors - Reiny**

Thank you for the help! "When I solved equations 2 and 3 I got u=0 and t=-1, giving me r = (-2,-3,0) in both r = ... equations." Ok I'll check that. I just have a question...how would you get r = (-2,-3,0) when u = 0 and t = -1?
*April 7, 2008 by Alex*