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Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

chemistry
how to calculate the oxidation state only for 'cr'in K2CRO4

Chemistry
Kg/m^2 is the unit of pressure how i prove it. Please help me.

Chemistry
Number of Oxygen atoms in 4.4g of CO2 is A)1.2×10^13 B)6×10^22 C)6×10^23 D)12×10^23 Please tell me correct option with the solution.

Chemistry
Write out the ionic and net ionic equations of Ca(OH)2 + HNO3 ---> Ca(NO3)2 + H2O

Chemistry
A 0,518 g sample of limestone was dissolved and then the calcium was precipitated as calcium oxalate ( CaC2O4). Afer filtrating the precipitate, it was needed 40,0 ml of KMnO4 0,250 N acidified with H2SO4 to titrate it. ¿ What is the %w of CaO in the sample? The equation for ...

chemistry
A sample of solid ammonia chloride NH4Cl, is dissolved in water...the solution found is acidic...explain why the solution is acidic?

Chemistry
I have a question related to oxidizing agents. Why do some oxidizing agents have to be in acid medium? For example the potassium permanganate. I would also like to know if there are other examples of oxidizing agents that have to be in acid medium or where I can find them.

College Chemistry
You have combined 1.218 moles of calcium ions and 0.943 moles of lithium ions in enough solvent to make 500.00mL of solution. What is the mole fraction of lithium ions in this solution? What type of problem is this and how do I set it up to solve?

Chemistry
How many moles of nitrate ions are present in 24.0mL of a 2.93M solution of potassium nitrate? I'm thinking this is some form of unit conversion problem I know that M= molarity which is mol/L how ever I am confused on how to set this up and input information or if I'm on the ...

Science, Chemistry
Using chemical equations, write the chemical reactions for the following; photosynthesis, combustion, corrosion of iron.

Chemistry
Find moles of O atoms in 9.00g of Mg(NO3)2.

Chemistry
Which of these will contain avogadro number of molecules: 1)22.4dm3 of co2 at 27∘c and 1atm contain 2)44g of at 27∘c and 1 atm 3)2.7dm3 of co2 at 546k and 2atm 4)11.2l of co2 at 273 and 2atm

Chemistry
Find the final temperature, given that the initial temperature of a 40 g piece of Aluminum is 25 degrees Celsius and it is heated with 1800 J of heat. The specific heat capacity of Aluminum is 0.903

Chemistry
Find moles of atoms in 9.00g of Magnesium nitrate. And please tell me method of typing molecular formula of any compound as of water or etc.

Chemistry
How many mL of 0.0257 N KIO3 would be needed to reach the end-point in the oxidation of 34.2 mL of 0.0416N hydrazine in hydrochloric acid solution

Chemistry
The molar mass of an organic acid was determined by the following study of its barium salt. 4.290 g of the salt were to be converted to the free acid by reaction with 21.64 mL of 0.477 M H2SO4. The barium salt was known to contain 2 moles water of hydration per mol Ba2+, and ...

chemistry
What is the balanced molecular,total ionic, and net ionic equations illustrating the reaction of magnesium hydroxide and HCl

chemistry
State two safe methods of distinguishing the acid from the base 1. 2. For each method above, state the results of both testing of the acid solution and the testing of the base solution. 1. 2.

Chemistry
What is the molar concentration of K4Fe(CN)6 solution if 40 ml were used to titrate 150 mg of Zn ( that are dissolved ) forming K2Zn3[Fe(CN)6]2 ? I really need help for this excersice , I don't know what to do... Note: In my book the answer is 0,0382 M

Chemistry
Assume that lemon Juice os 0.05M, the mass of the 5.0ml should be about 5 grams. So the Mass of acid in your sample is about 0.25 grams. Using this and the moles of acid calculate the gfm of the acid in the lemon juice. I was able to calculate moles, but do not know how to do ...

chemistry
How to prove that sodium hydroxide is a base with the help of an equation for the reaction

Chemistry
For an experiment, we used 10 mL of HCl. We are then to find the moles of it without any other information given. Is this right? (10 mL HCl)* (1.19 g / mL) = 11.9 g HCl (11.9 g HCl) * (1mol/36.46064 g) = 0.326 mols HCl

Chemistry
Which is a chemical change? A - splitting water into hydrogen and oxygen B - breaking a block of solid ice into smaller pieces C - freezing liquid water D - boiling water My answer: D

Chemistry
if a flask of 750 ml of 0.80m of nacl solution was left, and 275 ml evaporated, what is the new concentration

Chemistry
For the reaction C + 2H2 -> CH4 How many grams of hydrogen are required to produce 145 grams of methane, CH4

chemistry
why glycerol is used in cosmetics?

Chemistry
If methane burns with oxygen and form carbon dioxide and water,so why the carbon dioxide doesn't extinguish heat produced .

Chemistry
If the maximum velocity v of an electron in copper wire is about 2.0x10^8 cm/s, with an uncertainty ≤ 1%, how accurately can the electron's position be determined? In other words, what is the uncertainty in the position of the electron (in meters)?

Chemistry
Question: A solution of H2X of unknown concentration is given. pH of the solution is 4. ka1=2*(10)^-6 M ka2=1*(10)^-11 M Find the concentrations of [H2X] ,[HX-] and X^2- in the solution. My thoughts on the question: The temperature which the solution is kept is not given.So we...

Chemistry
You have found that 14.37mL of 0.162M sulfuric acid reacts with exactly 20.00mL of barium hydroxide solution of unknown concentration. What is the molarity of the barium hydroxide solution? Round your answer to 3 decimal places and include units. I know that this has something...

Chemistry-pH
Question: v cm3 of a 0.2 M HX solution and v cm3 of 0.1 M KOH solution is mixed.pH of the final solution is 5.3 1)Find ka of HX 2)Find the moles of NaOH and HCl should be added respectively,for the pH of 1dm3 of the solution to increase and decrease by 1 My thoughts on the ...

Chemistry
The equilibrium concentration of phosphate ion in a saturated chromium(III) phosphate solution is

chemistry
Look in the owner’s manual of your car to determine the amount of gasoline your tank can hold. Using the information presented in the text, calculate how much carbon dioxide is produced from driving your car for a year assuming that all the gas is octane (C8H18). You may not...

chemistry
Calculate the mole fraction of a mixture of NaBr and KBr which is 0.981g of mass, given that we are treating the mixture with excessive AgNO3. 1.690g of AgBr is formed.

Chemistry
If 6.0g of CH4 and 5.0g of O2 are used, what is the mass of CO2 produced?

Chemistry
Assuming that Raoults law is followed what would be the vapour pressure of a solution formed when 40g of sugar (molecular mass 342g) is dissolved in 360ml of water at 25oC? At 250C,the vapour pressure of water is 20mm and the density is 1g/ml.

Chemistry
Suppose you prepare a sample of paracetamol by reacting 10.0g of p-aminophenol with 15.0g of acetic anhydride. You obtain 10.8g of pure paracetamol as a product. What is the percentage yeild of the reaction?

Chemistry-kd
This equation you've mentioned in your answer to my recent question regarding kd, f=[1+(KD*Vo/Va)]^-(n) ,is this a general equation we can use directly? This is the first time I've come across with this..

Chemistry-kD
A chemical "X" is included in a water in a pond. 1)5dm3 of water from the pond is taken and is mixed with 200cm3 CHCl3.Then CHCl3 layer is taken out separately and left to vaporize. Then the remaining mass of X is measured.There was 10mg. 2)The remaining aqueous zone after (1...

Chemistry
Aluminum reacts with oxygen gas to produce aluminum oxide. How many moles of aluminum oxide would you expect to produce if you reacted 14.5 moles of oxygen gas with excess aluminum? 4Al +3O2 --> 2Al2O3 14.5 mol O2 x 4 mol Al / 3 mol O2 = 19.3 moles

Chemistry
Consider this reaction: Fe3O4(s)+4CO(g) --> 4CO2(g)+3Fe(s). If you begin with 0.03820 moles of iron oxide and 0.120 moles of carbon monoxide, how many grams of iron can be formed? Indicate which reactant is the limiting reactant. 0.03820 x 3/1= 0.1146 moles x 55.8 g 0.120 x...

Chemistry-titrations
Question: An unknown mass of (NH4)2CO3 is mixed with 4g of NaOH and dissolved in 100cm3 of water,which results a clear solution.Gasses are removed by heating the final solution. 2 parts of 25cm3 of final solution is taken and one is titrated with 0.5 M HCl and under Hph ...

chemistry
Why does honey diffuse in water at a slower rate than ink

chemistry
How change in humidity and temperature effects the rate of evaporation

chemistry
A hot lump of 46.9 g of copper at an initial temperature of 54.5 °C is placed in 50.0 mL of H2O initially at 25.0 °C and allowed to reach thermal equilibrium. What is the final temperature of the copper and water given that the specific heat of copper is 0.385 ...

Chemistry
Question: 50cm3 of 0.4 M Ba(OH)2 and 50cm3 of HA of unknown concentration is added together.At 25°C,pH of the solution is 9.With appropriate assumptions calculate the [HA] and ka of HA. My thoughts on the question: There are more than one approach which came to mind...I'll ...

Chemistry
Determine the concentration of 20.0 mL of the sulphuric acid when 1.00 mol/L sodium hydroxide is used as the titrant. Observations: Initial volume of H2SO4 __________. Final volume of H2SO4 __________. Volume of H2SO4 added __________.

Chemistry
Explain why the ethanol has a boiling point of 78.4degrees Celsius while dimethylether has a boiling point of -24degrees Celsius and they have the same mass molecular substances

Math
In an examination of a certain class, at least 70% of the students failed in Physics, at least 72% failed in Chemistry, at least 80% failed in Mathematics and at least 85% failed in English. How many at lest must have failed in all the four subjects ?

Chemistry
Calculate the mass of Fe(NH4)2(SO4)2.6H2O(s) required to prepare 25ml of 1.0 M Fe(NH4)2(SO4)2.6H20(aq)

Chemistry
A gas mixture is made by combining 7.2 g each of Ar, Ne, and an unknown diatomic gas. At STP, the mixture occupies a volume of 14.30 L. What is the molar mass of the unknown gas? Identify the unknown gas.

Chemistry
The standard electrode potential for Zn/Zn2+ and cu/cu2+ are -0.96volts and +0.3volts respectively at 293k.(a) calculate the free energy change when a zinc rod dips into 1M of zinc tetraoxosulphate(vi) solution and a copper rod dips into a 1M of copper (ii) tetraoxosulphate(vi...

chemistry(a mystery)
Which one is more reactive between chlorine and nitrogen and why?

Chemistry
How to prepare 50ml 0.04N H2SO4 from solution 0.025N sulfuric acid by adding 0.4N sulfuric acid

chemistry
3. A carbonate fusion was needed to free the Bi from a 0.6423-g sample of eulytite (2Bi2O3·3SiO2). The fused mass was dissolved in dilute acid, following which the Bi+3 was titrated with 27.36mL of 0.03369M NaH2PO4. The reaction is Bi+3 + H2PO4-  BiPO4(s) + 2H+. Calculate ...

chemistry
5. The tetraethyl lead [Pb(C2H5)4] in a 25.00-mL sample of aviation gasoline was shaken with 15.00mL of 0.02095M I2. The reaction is: Pb(C2H5)4 + I2  Pb(C2H5)3I + C2H5I. After the reaction was complete, the unused I2 was titrated with 6.09mL of 0.03465M Na2S2O3. Calculate ...

Chemistry-ksp and kb
We were given a 0.1 M KOH solution.25cm3 of that solution is taken and 5g of MX precipitate is added to that.X- is an anion of a strong acid. Kb for MOH=2*(10)^-5 Ksp for MX= 3*(10)^-6 M 1)find the [M+] in the solution 2)Find the [X-] concentration and pH of the solution. My ...

Chemistry
Calculate the number of mile contained in a solution of sulphuric acid, if the title value on titration against 20cm3, 0.5M sodium carbonate is 20. 24cm3 0.02mol 0.01mol 0.04mol 0.15mol

Chemistry
Crystallization process is restricted to_____________ Gas Liquids Solids Colloids

Chemistry
Crystallization occurs on_____________ Melting point Boiling point Cooling Freezing point

Chemistry
A method of separation useful for purification and isolation is________ Decantation Crystallization Evaporation Filtration

chemistry
Lab: Determining the Quantity of Vitamin C in Fruit Juice Vitamin C, also called ascorbic acid, is commonly found in commercial fruit juices and drinks. In this activity you will analyze data collected from a titration analysis of a fruit juice. The nutrition facts for a 200-...

Chemistry
What formula would you use to solve this problem? I'm stuck. You have prepared a solution by diluting 12.00mL of 0.790M copper(II) nitrate to a total volume of 50.00mL. What is the concentration of Cu2+ ions in the resulting solution? Report your answer to 3 decimal places.

Chemistry
*Please check to see if overall values are put in the right place!* Type of metal used= Copper Mass of metal object= 72.5 g Specific heat of copper= .385 J/g C° Mass of empty styrofoam cup= 3.264 g Mass of styrofoam cup & water= 142.3 g Temp of water (before)= 23.1 C° Temp ...

Chemistry
When 3.926g of NaOH is added to 100.0mL of water, the temperature of the solution increases by 28 degrees Celsius. Assume the density of the solution to be 1g/mL and specific heat capacity of the solution to be 4.184 J/gK. I'm unsure of which formula to use. I was going to use...

chemistry
Lab: Determining the Quantity of Vitamin C in Fruit Juice Vitamin C, also called ascorbic acid, is commonly found in commercial fruit juices and drinks. In this activity you will analyze data collected from a titration analysis of a fruit juice. The nutrition facts for a 200-...

chemistry
Lab: Determining the Quantity of Vitamin C in Fruit Juice Vitamin C, also called ascorbic acid, is commonly found in commercial fruit juices and drinks. In this activity you will analyze data collected from a titration analysis of a fruit juice. The nutrition facts for a 200-...

Chemistry
explain two different ways you could make 100ml of .500M solution of NaOH if you have an unlimited amount of water, 100g solid NaOH and a bottle of 2.0M NaOH.

chemistry
What volume of H2 is produced if excess nitric acid (HNO3) reacts with 46.3 g of magnesium 2HNO3 + Mg → H2 + Mg(NO3)2

Chemistry
If the back of your hand is moistened with alcohol, you will find that it rapidly becomes dry ,But if we do so with water it does not get dryer rapidly . Why?

Science/chemistry
CH4 + 2O2 --> OC2 + 2H2O What mass of water is formed by burning 4g of methane in excess oxygen? (Ar of carbon=12, Ar of oxygen=16 and Ar of hydrogen=1)

Chemistry
Methane (CH4) behaves as an ideal gas under standard temperature and pressure conditions. What volume is occupied by 1 kg of methane at a temperature of 35 °C and a pressure of 0.9 atm?

Chemistry
I know I am over thinking this problem like always but none of this makes sense to me for some reason.. KHP was used to determine the concentration of a KOH solution. If 0.78g of KHPwas used and 42.17 ml of KOH was used to titrate it to the endpoint what's it concentration? ...

chemistry
What's the aim of titrating potassium tetraoxomaganate(vii) with ammonium iron (ii) tetraoxosulphate (vi)

chemistry- morality
To what volume should 1.19 ml of an 8.00 m acetic acid solution be diluted in order to obtain a final solution that is 1.50 M? show all work

chemistry
Question : ka1 and ka2 values of H2X is given 1*(10)^-5 M and 1*(10)^-9 M.50cm^3 of 0.2 M KOH and 50 cm^3 of H2X of unknown concentration is mixed together and the pH of the final solution is given as 7. 1)Find the concentration of H2X 2)Find the pH of the initial H2X solution...

Chemistry
How many milliliters of a 5.15 M stock solution are needed to prepare 375 mL of a solution having 7.50 mg of methanol per mL of solution?

Chemistry
Question : ka1 and ka2 values of H2X is given 1*(10)^-5 M and 1*(10)^-9 M.50cm^3 of 0.2 M KOH and 50 cm^3 of H2X of unknown concentration is mixed together and the pH of the final solution is given as 7. 1)Find the concentration of H2X 2)Find the pH of the initial H2X solution...

Chemistry
What volume of a 0.500 M NaOH solution is needed to neutralize 60.0 mL of 0.15 M HCl solution?

chemistry
What will happen if ammonium chloride solution is used to standardize the potassium tetraoxomangate(vii)solution?

Chemistry
When 25.3 mL of 0.100 M NaOH was reacted with 18.8 mL of H2SO4 of unknown molarity, the final solution was 0.029207 M in H2SO4. What is the molarity of the original H2SO4 solution? The equation for the reaction is: 2 NaOH + H2SO4 → Na2SO4 + 2 H2O

Chemistry
Would glacial ethanoic acid have (l) or (aq) state symbol? I'm thinking liquid as it doesn't contain any water but would just like to confirm as struggling to find any equations involving it online? Thank you :)

Chemistry
The density of aluminum is 2.70 g/ml. What is the mass of a cube of Al that measures 2.20 cm on each side?(remember significant figures and to include the units of g in your answer, remember that 1 ml=1 cm3) Need help can someone go step by step so I can understand how to do it

chemistry (science)
explain the observed temperature change upon mixing ethanol and cyclohexane.

Chemistry
A solution is made by dissolving 10.20 grams of glucose (C6H12O6) in 355 grams of water. What is the freezing point depression of the solvent if the freezing point constant is -1.86 °C/m?

Chemistry
A substance has a molecular formula of C8H10N4O2. The empirical formula is -

Chemistry
If a 500ml brine is electrolysed with current of strength 0.5A,how many seconds would it take to achieve natural point

Chemistry
The electrolysis of 250ml of a brine solution was carried out for a period of 20mins with a current of 2A. The resulting solution was titrated with 0.62M HCL. How many ml of HCL would be required to achieve natural point

chemistry
Now use the average value of Kb the base dissociation constant of acetate anion to calculate an average value for Ka, the acid dissociation constant of acetic acid. Kb: 1.33x10^-10

Chemistry
Oxidation Numbers: My question to you is how did Al get a +3 Oxid.#, and S got 6... What is the mathematical explanation for that. I understand the rules that O is almost always -2 for its' oxid #. Would O be 10 bc you'd multple 4*3 and minus 2?

Chemistry - Significant Figures
Suppose it takes 35 min for 2.4 g of sugar to completely react with another reagent we added to the flask. What would the reaction rate be? Calculate to the correct number of significant figures.

chemistry
showing your work convert R=0.08206 atm dm^3 mol^-1 k^-1 to jmol^-1 k^-1

chemistry
explain why benzoic acid do not affect litmus paper

chemistry under gas law
convert the following. R=0.08206atm dm^3 mol^-1 k^-1 to jmol^-1 k^-1

chemistry ( little urgent pls)
For oxidation of iron 4Fe+3O2=2Fe2O3 the entropy change is -549.45JK^-1mol^-1 at 298K. Though it has negative entropy change in the reaction is spotaneous.why? (Delta r H theta ∆rH°=-1648×10^3 J ml^-1. Is it because ∆G is negative????

chemistry
If the pressure, volume, and temperature of a gas are known, which can most likely be found by using the ideal gas law?

Chemistry
Can anybody understand me about oxidising agent and reducing agent

erectlo chemistry
ADDIS ABABA UNIVERSITY ADDIS ABABA INSTITUTE OF TECHNOLOGY SCHOOL OF CHEMICAL AND BIO ENGINEERING Applied Electrochemistry WORKSHEET -1 1. Calculate the standard potential of each of the following cells. State which one(s), if any, will proceed spontaneously as written. a. Sn...

Organic chemistry lab
In the synthesis of salicylic acid from wintergreen oil, 5 ml of 20% NaOH was used, can it be used more or less than this amount?

chemistry
in which solvent is best suited to dissolve non-polar substances, water,ethanol or hexane

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