# Homework Help: Science: Chemistry

## Recent Homework Questions About Chemistry

chemistry
What is the equilibrium expression for the change when iron(II) chloride dissolves? FeCl2(s) Fe2+(aq) + 2Cl-(aq)

Chemistry
When a 0.326 g sample of FeCl2·xH2O is heated to remove all water, a mass of 0.254 g remains. Determine the value of x.

Chemistry
After you preform your experiment, you determine that the Kf value for naphthalene is 6.89 °C/m . You are using 10g of naphthalene and added 1.0 g of your unknown. The the freezing point of the solvent decreased by 4.42 °C when the unknown was added. Knowing this information...

Chemistry
How much ethylene glycol (C2H6O2, the major component of antifreeze) must be added to 1 L of water to keep it from freezing at -17 oC? Kf = 1.86 oC/m. I got 163.96 or 164 for my answer but that isn't correct and I don't know what I'm doing wrong.

chemistry
calculate number of ions of chloride in 444g of calcium chloride

chemistry
Acetylene (C2H2) burns with oxygen it gives CO2 and H2O. Write down it's Skelten equation?

Chemistry
Calculate the mass and moles of iodine that reacted in the formation of 2.7132 grams of ZnI2. im slighty confused about the use of iodine, would it be diatomic in the equation for example would i use the conversion 1 mol ZnI2 = 1 mol I2 or 1 mol ZnI2 = 2 mol I

Chemistry
How many milliliters of a 0.48 M HCl solution are needed to react completely with 7.4 g of zinc to form zinc(II) chloride? Answer in units of mL.

Physical Chemistry
5. Assume you have a 45°C 100g block of gold (cp=0.129J/g°C) and a 150°C , 150g block of silver (cp=0.240J/g°C)(1). You place these blocks into an adiabatic container in thermal contact. a. Calculate the final temperature b. Calculate the heat transferred c. Describe how ...

chemistry
Which of the following is an ortho directing group? a) CN b) CO2Me c) OMe d) NO2 I have drawn most of them out, CN has no delocalised electrons to contribute e- density hence EWG. For NO2 inductive effect is strong and hence is a EWG and meta directing. OME EDG -> Ortho im ...

Chemistry
Your lab partner tells you that he has prepared a solution that contains 1.5 moles of NaOH in 1.5 L of aqueous solution, and therefore that the concentration of NaOH is 1.5 M. (a) Is he correct (b) If not what is the correct concentration

Chemistry (equilibrium)
C2H6(g) <=> C2H2(g) + 2 H2(g) The ΔH° for the reaction above is +312 kJ. The system is initially at equilibrium. In which direction will the reaction shift in each of the following situations? e) The temperature is decreased. g) He is added at constant volume. h) ...

science ap chemistry
What is the equilibrium expression for the following acid dissociation reaction? CH3COOH + H2O CH3COO- + H3O+ A. [CH3COO-][H3O+]/[CH3COOH][H3O] B. [CH3COOH][H2O]/[CH3COO-][H3O+] C. [CH3COOH]/[CH3COO-][H3O-] D. [CH3COO-][H3O+]/[CH3COOH]

chemistry help
Which of the following is true of the solubility product constant? A. It is the product of the initial concentrations of the ions in a solution. B. It is an equilibrium constant. C. It is an equilibrium position. D. Its value changes in the presence of a common ion.

chemistry help
During a chemical reaction, if Q = K, what can be said about the reaction? A. The reaction still proceeds in both directions, but the net result is that the reactant and product concentrations do not change. B. The amount of product is always equal to the amount of reactant. C...

chemistry help
How does too little acid cause gastric distress? A. More than enough acid is present to digest proteins, resulting in inadequate digestion of proteins. B. The pH of the stomach becomes so high that proteins are not digested properly. C. The pH of the stomach becomes so low ...

chemistry
Which of the following statements is true of a solution at pH 7? A. Kw and Kb are equal. B. Kw and Ka are equal. C. Kw, Ka and Kb are equal. D. Ka and Kb are equal.

Chemistry
What is the name of the compound NO3. (Not NO3-, nitrate)???? Please help!

chemistry
Which of the following is true about the results of a neutralization reaction? A. An acid and a base form water and salt. B. Water reacts with a base to form the hydroxide ion. C. Water reacts with an acid to form the hydronium ion. D. An acid and a base dissociate into their ...

chemistry
A precipitate of copper(II) hydroxide is formed in a reaction. What change will help to dissolve the copper(II) hydroxide? Cu^2+(aq) + 2OH^-(aq) Cu(OH)"subtext"2(s) A. Adding NaOH B. Adding HCl C. Removing CuCl2 D. Removing H2O is the answer for this d? removing H2O??

chemistry
Which of the following is true of the solubility product constant? A. It is the product of the initial concentrations of the ions in a solution. B. It is an equilibrium constant. C. It is an equilibrium position. D. Its value changes in the presence of a common ion.

chemistry
What happens to the following reaction at equilibrium if the pressure is decreased? 2H"subtext"2(g) + O"subtext"2(g) 2H"subtext"2O(g)

chemistry
Which statement describes a chemical reaction at equilibrium? A. The forward reaction happens slightly faster than the reverse reaction. B. The reaction has stopped because all reactants have been used up. C. The forward reaction happens at the same rate as the reverse ...

chemistry
A 1.272 g sample of a mix Na2CO3 and NaHCO3 vol of 0.24 N HCl required for PP end point 26.92 ml after the addition 52.21 ml more of the HCl and boilling out CO2 the vol of 0.12 NaoH required to give a pink colour to the soln = 4 ml

math or chemistry
5.4 x10^-2 by 2.5 x10^-3 by 7.9 x10^-3m volume = 106.65 x10-8m^3 Check pls yesterday you said 106.65 x10^-6. If you add 2+3+3 you get 8 is that right? Just want to make sure I'm doing it right. Thank you. I may have witten it differently.

chemistry
Vinegar is a solution of acetic acid, a weak acid. How can you produce more acetate ions in the solution? CH 'subtext' 3 COOH(aq) H+(aq) + CH 'subtext' 3 COO^- (aq) A. Evaporate some of the water. B. Decrease the pressure. C. Increase the volume of the container. D. Add more ...

Chemistry
How does hybridisation of PCL5 change when it is decomposed to PCL3 and Cl2?

chemistry
Sig figs 33.067. 5 sig figs .0908. 3sig figs 1099. 4 .0087. 2 check pls

math or chemistry
Check pls. 5.4 x 10^-2 by 2.5 x 10^-3 by 7.9 x10^-3 m volume = 107.44 x 10^-8 m^3

chemistry
05 mL of sample water needs10.9 mL .01M EDTA solution. what is the accurate Hardness of sample in CaCO3 (mg/L)? pls expalin.

Chemistry
For my lab, I have been asked to calculate the pKa of an unknown amino acid. We titrated the unknown amino acid with NaOH. The pKa needs to be calculated using the Henderson Hasselbach Equation. Obviously you can just get the pH from any point on the graph but what values do ...

Chemistry urgent please
How much mL of dilute nitric acid is needed to add in control solution in chloride limit test in sodium hydroxide sample???can u please give me Answer urgently??

Chemistry
The density of an unknown gas is 1.23 g/L in 330K and temperature 25.5 pressure kPa. What is the molar mass of the substance?

Chemistry
Ammonia is composed of hydrogen and nitrogen in a ratio of 9.33 g of nitrogen and 2.00 g of hydrogen. if a sample of ammonia contains 6.28 g of hydrogen, how many grams of nitrogen does it contain?

chemistry
Which of the following reactions have a positive delta S rxn? check all that apply 1) A(s)+2B(g) -->C(g) 2) 2A(g)+3B(g) -->4C(g) 3) 2A(g)+2B(g) -->5C(g) 4) 2A(g)+B(s) -->3C(g) Not sure how to tell if the reaction is positive.

Chemistry
Calculate the degree of dissociation and oh conc in 0.1m (nh4)3po4 having alpha 50%

Chemistry(please check my answer)
The transuranium elements A. are the elements with atomic numbers above 92. *** B. occur in nature. C. are sometimes radioactive. D. all of the above

chemistry
If 100 g of butane are reacted with unlimited amounts of oxygen, how much carbon dioxide (in grams) and how much water (in grams) should form?

Chemistry
What changes of state are involved in this use of ethyl chloride? Select all that apply. Select all that apply. 1-liquid to gas 2-liquid to solid 3-gas to solid 4-liquid to solid 5-solid to liquid 6-solid to gas

Chemistry
2CO(g) + O2(g) -> 2 CO2(g). What volume of oxygen is required at 25 degrees celcius? This is all the information the question come with, and I am not sure if there might be something missing?

chemistry
a) What is fellesioneffekten?   Veronal is a barbiturate (structure see above). Barbiturates is a substance class which occur in a variety of drug classes, including sleep medications (hypnotikasedativa), in painkillers (anesthetics) and anticonvulsants. A barbiturate is a ...

Chemistry
2CO(g) + O2(g) -> 2 CO2(g). What volume of oxygen is required at 25 degrees celcius? This is all the information the question come with, and I am not sure if there might be something missing?

Chemistry
2CO(g) + O2(g) -> 2 CO2(g). What volume of oxygen is required at 25 degrees celcius? This is all the information the question come with, and I am not sure if there might be something missing?

chemistry
a) What is fellesioneffekten?   Veronal is a barbiturate (structure see above). Barbiturates is a substance class which occur in a variety of drug classes, including sleep medications (hypnotikasedativa), in painkillers (anesthetics) and anticonvulsants. A barbiturate is a ...

chemistry
In quality control of raw materials for pharmaceutical production often used foul reactions to prove that raw materials in salt form containing the appropriate salt. Hydrochloride (eg. Amitriptyline hydrochloride) can be detected for example by precipitating the chloride ions...

chemistry
Cocaine is a weak base (Figure see below) with pKb = 5.59. Cocaine has local anesthetic effect (local anesthetic) but is also a narcotic.   a) Calculate the ratio of the concentration of cocaine and its conjugated acid in a solution which has. pH = 7.40 (that of blood) ii. ...

chemistry
To create a 0.1 M carbonate buffer pH = 10.2. You choose to use a combination of HCO3- / CO32-. This buffer system has pKa = 9.9.   a) Calculate how much you need to weigh in each of the sodium salts, NaHCO3 and Na2CO3, to create 1.0 L carbonate (with total concentration of ...

chemistry
a) Hva er fellesioneffekten? Veronal er et barbiturat (struktur se over). Barbiturater er en stoffklasse som forekommer i en rekke legemiddelgrupper, blant annet i sovemedisiner (hypnotikasedativa), i smertestillende (anestetika) og i antiepileptika. Et barbiturat er en svak ...

chemistry
Calculate the pH reaches 30.0 mL one 0.200 M solution of HCl salt of amitriptyline is added 100.0 mL of a NaOH solution of concentration 80 mM.

chemistry
Calculate the pH at 25 ° C when 120 mL of a HCl solution having a concentration of 50 mM is added 50.0 mL of a 120 mM ephedrine solution. Assume no change in temperature.   Amitriptyline is a drug used in treating depression. It is typically formulated as the hydrochloride ...

chemistry
presentation Tasks:  Ephedrine (structure see below) is a natural product that is used as a medicine in the treatment of asthma. The corresponding acid to ephedrine have pKa = 9.60 at 25 ° C.   Question:  Calculate the pH reaches 991 mg ephedrine dissolved in 50.0 mL of ...

Chemistry
I have a homework question that says: "Three resonance structures of the following anion are possible. One is given below, but it is incomplete. Complete the given structure by adding non-bonding electrons and formal charges. Draw the two remaining resonance structures, ...

chemistry
Why one mole of sulfuric acid needs two moles of sodium hydroxide explain by avogadro's concept?

Chemistry
What is the osmotic pressure of blood plasma at 37°c

chemistry
The oxidation of NO by O3 is first order in each of the reactants, and its rate constant is 1.5 ´ 107 M-1·s-1. If the concentrations of NO and O3 are each 5.0 ´ 10-7 M, what is the rate of oxidation of NO in M·s-1?

chemistry
The oxidation of NO by O3 is first order in each of the reactants, and its rate constant is 1.5 ´ 107 M-1·s-1. If the concentrations of NO and O3 are each 5.0 ´ 10-7 M, what is the rate of oxidation of NO in M·s-1?

chemistry
How many grams of nacl are required to completely neutralize 100 ml of 1M h2so4?

Chemistry
Why is it that copper (II) sulfate with barium hydroxide --> copper hydroxide (solid) + barium sulfate (solid)? According to the solubility rules given to me by my professor, both are insoluble, and therefore should be labeled as solids. Is there something I'm missing here...

Chemistry
Why is it that copper (II) sulfate with barium hydroxide --> copper hydroxide (solid) + barium sulfate (solid)? According to the solubility rules given to me by my professor, both are insoluble, and therefore should be labeled as solids. Is there something I'm missing here...

AP Chemistry
The reaction of 5.7 grams of fluorine with excess chlorine produced 7.6 grams of ClF3. What percent yield of ClF3 was obtained? Answer in units of %.

Chemistry
A saline solution used in intravenous drips for patients who cannot take oral fluids contains 0.92% (w/v) NaCl in water. How many grams of NaCl are contained in 250 mL of this solution? So wouldn't it just be .92%= .92 grams x 250ml.../100= 2.3 g NaCl?

Chemistry
Larry has 250.00 ml of water. The water currently holds the maximum amount of soluble Silver iodide. In a separate container, Larry has 96 ml of a 0.07M solution of sodium carbonate. He wants to precipitate out all of the silver. Of his 96 ml, how much will he have to pour ...

Chemistry
Using a closed system experiment will a leak during gas evolving reaction overstate or understate the amount of sodium bicarbonate in an alka seltzer cold tablet?

Chemistry
Element X has 6 protons, 8 neutrons, and 6 electrons. Predict the atomic mass of element X?

chemistry
How do you separate this into ions Na2B4O7

Chemistry
Do you think the copper and zinc underwent a physical change or a chemical change?

Chemistry
A scientist used 21.0g of NaHCO3. How many miles of NaHCO3 were in this sample?

Chemistry
How many grams of NaOH would you dissolve in pure water to make 400 mL of a 2.5% NaOH solution ? MW of NaOH = 40 g/mol

Chemistry(please check my answer)
When a radioactive isotope undergoes Beta Decay, which of the following will NOT occur? A. The mass number of the original nucleus changes. B. The atomic number of the original nucleus changes. C. The original nucleus approaches greater stability. D. Energy is released.***

Chemistry(please check my answer)
A radioactive isotope of radium (Ra-226) has a half-live of 1620 years. How much of this isotope remains after three (3) half-lives? A. 1/2 B. 1/4 C. 1/8*** D. None

Chemistry(please check my answer)
Which of the following is true concerning gamma radiation? A. The mass number of the radioisotope decreases by four. B. The atomic number of the radioisotope decreases by two. C. The atomic number of the radioisotope increases by one. D. Neither the mass number nor the atomic ...

Chemistry
"Aluminum metal melts at 658.5°C. What would be the final temperature if 28.0 grams of solid aluminum at this temperature were placed into 520 grams of liquid aluminum at 1000.0°C? The heat of fusion for aluminum is 396 J/g, and the specific heat of liquid aluminum is 0.481 ...

Organic chemistry
How many nodes are in the pi* orbital of a carbon-carbon double bond? Please explain. Thanks in advance.

chemistry
student places a 23.80 g solid metal object in a graduate cylinder containing 26.5 mL of water. The water level increases to 32.1 ml after the object is submerged. Calculate the density of the object.

Chemistry
Confused, conflicting texts when you are finding % error for density formula: experienced value-accepted value/ accepted value ×100. Does the ×100 cancel out the percent sign? EX; 7.28g/mL-6.54g/mL/6.54g/mL ×100. Is the answer 11.31 or 11.31% The lab video did not multiply ...

chemistry
calculate the mass of silver deposited when a current of 3ampere is passed through a solution of a silver salt for 7minutes

ma
In a class of 100 students, 40 failed in Math, 30 failed in Physics, 60 failed in Chemistry. 35 passed in both Math and Physics. 20 passed in Physics and Chemistry. 25 passed in Math and Chemistry. Each student passed in at least one subject. How many students passed in all ...

chemistry
mass of empty flask plus stopper 36.765 g mass of stoppered flask plus water 65.264 g Temperature 24.8 C calculate the volume? need help please

Chemistry
One isotope of a metallic element has mass number 10 and has 7 neutrons in the nucleus. It forms an atomic ion having 2 electrons. Enter the symbol for this ion

physics
How do the laws of physics apply to others sciences such as biology chemistry and earth science? And give an example to show the connection.

Chemistry
Upon decomposition, one sample of Magnesium Fluoride produced 1.65 kg of magnesium and 2.57 kg of fluorine. A second sample produces 1.33 kg of magnesium. How much fluorine (in grams) did the second sample produce?

Chemistry
"Calculate the enthalpy of vaporization of water given that, when 5.00 grams of steam (gaseous H2O) at 100°C was introduced into a beaker containing 500 grams of water at 20.0°C, the temperature rose to 26.2°C." q_H2O(l) + q_H2O(g)= E nΔH_vap + m_gasCΔT + m_H2O(l)...

Chemistry
"Aluminum metal melts at 658.5°C. What would be the final temperature if 28.0 grams of solid aluminum at this temperature were placed into 520 grams of liquid aluminum at 1000.0°C? The heat of fusion for aluminum is 396 J/g, and the specific heat of liquid aluminum is 0.481 ...

Chemistry - Enthalpy
"Calculate the enthalpy of vaporization of water given that, when 5.00 grams of steam (gaseous H2O) at 100°C was introduced into a beaker containing 500 grams of water at 20.0°C, the temperature rose to 26.2°C." H2O (l) -> H2O (g) ΔH = ΔH_vap 5g H2O (g) @ 100°...

Chemistry
1.What two sets of units can be used to describe density? Why are they interchangeable? ~~~~~ I'm not sure what it means with units? Like grams and such? And what do they mean by interchangeable?

chemistry
how do i prepare a sulphuric acid solution having 75 % purity with 1.68 specific gravity from sulphuric acid with 97 % purity and 1.834 specific gravity.

Chemistry
How much heat is evolved in converting 1.00 mol of steam at 155.0 ∘C to ice at -45.0 ∘C? The heat capacity of steam is 2.01 J/(g⋅∘C) and of ice is 2.09 J/(g⋅∘C).

Chemistry
How many grams of ice are needed to cool 250 ml of water from 75 degrees Celsius to 5 degrees Celsius? (m_ice * 6.01kJ) + (m_ice * 4.18J/g°C * (5-75°C) = -[250mL * 4.18J/g°C * (5-75°C)] ???

Chemistry
A piece of metal with a mass of 131 g is placed in a 50 mL graduated cylinder. The water level rises from 20. mL to 35 mL. What is the density of the metal?

P-Chemistry
A closed vessel of volume 2.50 dm3 contains 100g of nitrogen (N2) and 100g of carbon dioxide (CO2) at 25 C. What are the partial pressures and mole fractions of each gas? Can you check my answers.Thank you. I got Partial Pressure for N2=34.95 atm CO2=22.24 atm Mole fraction of...

P-Chemistry
A closed vessel of volume 2.50 dm3 contains 100g of nitrogen (N2) and 100g of carbon dioxide (CO2) at 25 C. What are the partial pressures and mole fractions of each gas?

Chemistry
two aqueous solutions (solution A and solution B) contain different non reactive solutes and have densities of 1.021 g/ml and 1.190 g/ml, respectively. when 40.00 ml of solution A is mixed with 10.00ml of solution B what is the density of the mixture? im not entirely sure how ...

Chemistry Help Please!
At most, how many 4d electrons can an atom have? Of these what is the maximum number that can have ms= -1/2? A 5f electron has what value of quantum number l? What values of ml may it have? Also please explain how you got the answers so I can understand? Thank you so much!

Chemistry
Why is it important to keep the beaker containing the mobile phase covered while preparing your chromatography paper and developing your chromatograms?

chemistry
i.Calculate the volume of carbon ivoxide given off at stp when 20gram of octane is burnt in excess air (c=12,1+=1 gmv of any gass is 22.4dm^3 at stp). ii. Deduce the formula of a hydrocarbon with general formula cnH2n-2 of its molar mass in 110.

Chemistry
If the density of carbon is 3.51 g/cm3, and you have a small diamond (pure carbon) that has a mass of 0.0270 grams, what is the volume?

Analytical Chemistry
Calculate the hydroxide concentration of a solution that is 0.1 F with NH3, and 0.25 F in respect to (NH4)2S04.

Chemistry
How much heat energy is required to heat up 50.0 grams of water from 20.2 degrees Celsius to 34.2 degrees Celsius? I want o use the Q=mc(change in temp) formula but I am only given the m and difference in temp in this question so I am not sure of what I am supposed to do.

Chemistry
The density of diamond is 3.51g/cm^3,and the density of platinum is 21.43g/cm^3.If equal masses of diamond and platinum are transferred to equal volumes of water in separate graduated cylinders,which graduated cylinder would have the greatest volume change? Explain or show ...

Chemistry
At 603 K, Kc for the reaction NH4Cl <===> NH3 + HCl is 0.011. What is the equilibrium concentration of NH3 if the initial concentration of NH4Cl is 0.500 M. Please help me with this question because i got 2 answers so prove me.

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