# Chemistry-help needed

64,130 results

### chemistry 2

You are instructed to create 800. mL of a 0.69 M phosphate buffer with a pH of 7.6. You have phosphoric acid and the sodium salts NaH2PO4, Na2HPO4, and Na3PO4 available. what is the molarity needed for the acid component of the buffer?What is the molarity needed for the base ...

### chemistry

what is the number of grams needed to prepare a 1.23 M solution of nitric acid if 250.0 mL are needed?

### Chemistry help needed

How many milligram of lysozyme (MW=14,600 g/mol) are needed to make 3 liters of a 10^-6 M solution?

### chemistry

a student needed 1000 ml of a 0.10 buffer of ph 4.0. calculate the amount of sodium acetate and acidic acid needed for this solution

### Chemistry please help!

Please help. I have no idea how to do these 4 homework problems. 1- How many milliliters of 0.140 M HCl are needed to completely neutralize 42.0mL of 0.106 M Ba(OH)2 solution? 2-How many milliliters of 0.123 M H2SO4 are needed to neutralize 0.250 g of NaOH ? 3-If 55.2 mL of ...

### Chemistry..

A chemical engineer calculated that 15.0 mol H2 was needed to react with excess N2 to prepare 10.0 mol NH3. But the actual yield is 60.0% . Write a balanced chemical equation for the reaction. Is the amount of H2 needed to make 10.0 mol NH3 more than, the same as, or less than...

### chemistry

suppose i want to find out how many mL of 1.0M AgNO3 are needed to provide 169.9g of pure AgNO3. what is step one in solving this problem? How many mL of solution are needed?

### Chemistry

Record the amount of heat needed to change phases for water-ice to steam using graphical analysis. Is there a one accurate amount of heat needed to change phases, I thought it varied depending the problem... Would the question be asking for the heat needed in my graph that I ...

### Chemistry

If 62.7 ml of .208M HCL is needed to needed to neutralize a solution of Ca(OH)2, how many grams of Ca(OH)2 must be in the solution?

### Chemistry

Calculate the mass of copper needed to displace 5.0g of silver from silver nitrate solution. Cu+2AgNO3->Cu(NO3)2+2Ag (Relative atomic masses:Ag=108,Cu=63.5) I got it to be 3.175g needed.

### math

Draw a venn diagram to illustrate the following. In a shop 50 cars were inspected and it found that 23 needed new brakes and 34 needed new tires. 3 needed no services at all how many needed new brakes and new tires? How many only needed brakes? Please help

### Chemistry Solubility help!!!!!!!!!

INFORMATION: [HCl] = 0.1388 M We placed 0.5 g Ca(OH)2 in 100 mL of the following solutions: Flask A: Distilled Water (7.4 mL of HCl needed to titrate) Flask B: 0.05 NaOH (12.1 mL of HCl needed to titrate) Flask C: 0.025 NaOH (10.8 mL of HCl needed to titrate) Flask D: 0.0125 ...

### chemistry

Calculate the energy needed to produce 10 moles of Cl2O7 using this balanced equation. 2Cl +70+ 100kCal==2ClO7 please explain steps if I needed to calculate for 7 moles, how would it change?

### Chemistry

Why is the temperature needed to freeze ocean water lower than the temperature needed to freeze the surface of a freshwater lake?

### Chemistry

Calculate the volume of 2.45 M NaI that would be needed to precipitate all of the Hg+2 ion from 185 mL of a 2.44 M Hg(NO3)2. AND Calculate the molarity of an acetic acid solution if 47.81 mL of the solution is needed to neutralize 147 mL of 1.32 M sodium hydroxide.

### Chemistry - Solubility

INFORMATION: [HCl] = 0.1388 M We placed 0.5 g Ca(OH)2 in 100 mL of the following solutions: Flask A: Distilled Water (7.4 mL of HCl needed to titrate) Flask B: 0.05 M NaOH (7.5 mL of HCl needed to titrate) Flask C: 0.025 M NaOH (10.8 mL of HCl needed to titrate) Flask D: 0....

### Chemistry - Solubility

INFORMATION: [HCl] = 0.1388 M We placed 0.5 g Ca(OH)2 in 100 mL of the following solutions: A 25 ml aliquot was used Flask A: Distilled Water (7.4 mL of HCl needed to titrate) Flask B: 0.05 M NaOH (7.5 mL of HCl needed to titrate) Flask C: 0.025 M NaOH (10.8 mL of HCl needed ...

### Chemistry Help Please!!

We did an experiment and I don't really know how to calculate this question. If you could show me how to do one, then I could do the rest. INFORMATION: HCl = 0.1404 M We placed 0.5 g Ca(OH)2 in 100 mL of the following solutions: Flask A: Distilled Water (8.5 mL of HCl needed ...

### Chemistry HELPP!!!!!!

We did an experiment and I don't really know how to calculate this question. If you could show me how to do one, then I could do the rest. INFORMATION: HCl = 0.1404 M We placed 0.5 g Ca(OH)2 in 100 mL of the following solutions: Flask A: Distilled Water (8.5 mL of HCl needed ...

### chemistry

how do i do this \? a 4.0mg/dl standard solution is needed. To prepare 100ml of the working standard. How much stock standard of a 1mg/ml (100mg/dl) solution is needed. i don't understand this conceptually / thanks

### Chemistry

Suppose you wanted to find out how many milliliters of 1.0 M AgNO3 are needed to provide 169.88 g of pure AgNO3. a. What is step 1 in solving the problem? b. What is the molar mass of AgNO3? c. How many milliliters of solution are needed?

### Chemistry

How would you prepare 165 mL of a 0.976 M NaOH solution, starting with a 6.36 M stock solution? Volume of solution needed? Volume of water needed?

### Science - Chemistry

Aluminum oxide is formed from the reaction of metallic aluminum with oxygen gas. How many moles of Aluminum are needed to form 3.4 moles of Aluminum oxide? Writr the equation and balance it. 4Al + 3O2 ==> 2Al2O3 The equation tells you that 4 mols Al are needed to form 2 ...

### Algebra- word problem

Jordan has a photograph on his wall that is 3 in. long and 6 in. wide. He takes it to be framed which increases the length and width by 2 in. each. How does getting the picture framed change the amount of wall space needed? My choice is B- Correct?? Choices A. the wall needed ...

### Chemistry

I need to calculate the amount of NaH2PO4 (in grams) and 1.00M NaOH solution (in ml) needed to make 250 ml of 0.20M H2PO4- at pH 8.00. My work is lengthy and involved but the answer I got was 7.00 ml of the NaOH and 0.0070 moles of the NaH2PO4 needed. Can you tell me if I am ...

### Chemistry

I need to calculate the amount of NaH2PO4 (in grams) and 1.00M NaOH solution (in ml) needed to make 250 ml of 0.20M H2PO4- at pH 8.00. My work is lengthy and involved but the answer I got was 7.00 ml of the NaOH and 0.0070 moles of the NaH2PO4 needed. Can you tell me if I am ...

### Grade 11 Chemistry!

10% (m/m) sodium hydroxide solution, NaOH, is used to break down wood fibre to make paper. a) What mass of solute is needed to make 250mL of 10% (m/m) solution? b) What mass of solvent is needed? c) What is the molare concentration?

### Chemistry

What is needed for nuclear fusion to occur? pressure, a beta particle or high temperature? I think it's only high temperature and pressure needed.

### Chemistry

1 N204(l) + 2 N2H4(l) --> 3 N2(g) + 4 H2O(g) If you start with: 5.0 x 10^4 g hydrazine (N2H4) "in the tank": 1) How many moles of nitrogen can be created (assuming 100% yield)? 2) How many moles of water can be produced? 2) What mass of dinitrogen tetroxide (N2O4) is needed...

### Health

1. What is needed to make blood cells? 2. What pair of workers is needed to produce estrogen? 3. What is needed to produce eleven hormones that control the actions of other endocrine glands? 4. What is needed to pass oxygen from lungs into blood vessels and welcome carbon ...

### Chemistry

1 N204(l) + 2 N2H4(l) --> 3 N2(g) + 4 H2O(g) If you start with: 5.0 x 10^4 hydrazine (N2H4) "in the tank": 1) How many moles of nitrogen can be created (assuming 100% yield)? 2) How many moles of water can be produced? 2) What mass of dinitrogen tetroxide (N2O4) is needed? ...

### Chemistry

10% (m/m) Sodium Hydroxide solution, NaOH(aq) is used to break down wood fibre to make paper. A) What mass of the solute is needed to make 250mL of 10% (m/m) solution? B) What mass of solvent is needed? C) What is the molar concentration of the solution?

### Chemistry

How many grams of CaCl2 are needed to prepare 25.0 mL of .500 M solution? and What volume of 12.00 M HCL is needed to prepare 150.0 mL of .500 M HCL?

### Chemistry

My questions keep getting cut off. What am I doing wrong? Here is my question again. Thanks for the help. What is the empirical formula for a compound whose molecular formula is C2Cl6? a) CCl3 b) CCl4 c) C2Cl6 d)CCl e) more info needed I think the answer is E more information ...

### Chemistry

Balanced Chemical Equation: 1 N204(l) + 2 N2H4(l) --> 3 N2(g) + 4 H20(g) If you start with: 5.0 x 10^4g hydrazine (N2H4) "in the tank": 1) How many moles of nitrogen can be created (assuming 100% yielded)? 2) How many moles of water can be produced? 3) What mass of ...

### Chemistry

Balanced Chemical Equation: 1 N204(l) + 2 N2H4(l) --> 3 N2(g) + 4 H20(g) If you start with: 5.0 x 10^4g hydrazine (N2H4) "in the tank": 1) How many moles of nitrogen can be created (assuming 100% yielded)? 2) How many moles of water can be produced? 3) What mass of ...

### chemistry

1998 scientists using a special type of electron microscope were able to measure the force needed to break a single chemical bond. If 2.0 x 10^-9 N was needed to break a C-Si bond, estimate the bond enthalpy in kJ/mol. Assume that the bond had to be stretched by a distance of ...

### Chemistry

1. What is the molar of a sodium bicarbonate solution prepared from 150 g of NaHCO3 in 150 mL solution? 2. What mass of glucose (C6H12O6) is needed to prepare a solution of 10 M, 5 L solution? 3. What volume in liters of a 4.0 M Ca(NO3)2 is needed to provide 50 g Ca(NO3)2?

### Chemistry

What partial pressure of oxygen above the water (in atmospheres at 0 C ) is needed to obtain this concentration? The solubility of O2 in water at 0 C and 1 atm partial pressure is . 2.21 x 10^-3 mol/L Concentration needed is 4mg/L Stuck and need help, anything is appreciated!

### Chemistry

How many grams of a stock solution that is 87.0 percent H2SO4 by mass would be needed to make 200 grams of a 35.5 percent by mass solution? Show all of the work needed to solve this problem.

### Chemistry

How many grams of a stock solution that is 85.5 percent H2SO4 by mass would be needed to make 150 grams of a 45.0 percent by mass solution? Show all of the work needed to solve this problem.

### Chemistry

CH4 + 2O2 --> CO2 + 2H2O a. How many grams of methane are needed to produce 1.5 X 10^-2 grams of carbon dioxide? b. How many grams of oxygen are needed to react to form the 1.5 X 10^-2 grams moles of carbon dioxide?

### Chemistry

CH4 + 2O2 --> CO2 + 2H2O a. How many grams of methane are needed to produce 1.5 X 10^-2 grams of carbon dioxide? b. How many grams of oxygen are needed to react to form the 1.5 X 10^-2 grams moles of carbon dioxide?

### Chemistry

CH4 + 2O2 --> CO2 + 2H2O a. How many grams of methane are needed to produce 1.5 X 10^-2 grams of carbon dioxide? b. How many grams of oxygen are needed to react to form the 1.5 X 10^-2 grams moles of carbon dioxide?

### Chemistry

WOULD THE VOLUME OF A 0.10M NAOH SOLUTION NEEDED TO TITRATE25.0ML OF A 0.10M HNO2 ( A WEAK ACID)SOLUTION BE DIFFERENT FROMTHAT NEEDED TO TITRATE 25.0ML OF A 0.10M HCL (A STRONGACID)SOLUTION?

### Chemistry

What mass of helium gas is needed to pressurize a 98.0 L tank to 165 atm at 21 °C? What mass of oxygen gas would be needed to pressurize a similar tank to the same specifications

### chemistry

Another “grand challenge” for engineering is managing the nitrogen cycle. Use the nature of the chemical bond in diatomic nitrogen to explain why any management is needed for this biogeochemical cycle. With so much nitrogen available in the atmosphere, why are engineering ...

### Algebra ll

Cleopatra was needed barge workers, and when the word went out 175 workers showed up, that is 21/2 times the amount needed. How many workers were originally needed? (I am trying to help my niece with her homework, and we live 600 miles apart. Can you explain to me how to get ...

### AP CHEMISTRY

1) Calculate the molarity of a solution of sodium hydroxide, NaOH,if 23.64 mL of this solution is needed to neutralize 0.5632g of potassium hydrogen phthalate. 2) It is found that 24.68 mL of 0.1165M NaOH is needed to titrate 0.2931 g of an unknown acid to the phenolphthalein ...

### Chemistry

Balance the following equation for a half reaction that occurs in acidic solution. Use e– as the symbol for an electron. U^4+ --> UO2^+ There is a hint: In acidic solution, you may add H2O and H as needed to balance oxygen and hydrogen. When finished, don\'t forget to ...

### CHEMISTRY

4. The human eye is a complex sensing device for visible light. The optic nerve needs a minimum of 2.0 x 10-17 J of energy to trigger a series of impulses that eventually reach the brain. (a) How many photons of red light (700.0 nm) are needed? (b) How many photons of blue ...

### chemistry

A student needed to make 200 ml of 0.1 M naOH. If the stock soluton was 0.75 M, how much of the stock solution and how much wter would be needed to make this solution?

### CHEMISTRY

How much heat is needed to melt 150g of ice? and How much heat is needed to change 150g of ice into steam at 110 degrees? My heat of fusion is 361 and my percent error is 8 if you need that. Answers quickly please :(

### chemistry

How do I find out how many ml of NaOH i need to titrate H3PO4. I used the ice table to knock off the two protons but im using a .2200M NaOH and do not Know how to determine the volume needed before hand. In other words i need some pre-calculations for volume of titrate needed ...

### chemistry

The Fe(ox)33– complex ion creates an emerald green solution when dissolved. The observed solution color of the complex indicates the size of o is: A. large. B. small. C. in between. D. inconclusive, more information is needed. The observed solution color of the complex ...

### chemistry

he Fe(ox)33– complex ion creates an emerald green solution when dissolved. The observed solution color of the complex indicates the size of o is: A. large. B. small. C. in between. D. inconclusive, more information is needed. The observed solution color of the complex ...

### chemistry

If 13.5 ml of concentrated (17.0 M) of sulfuric acid was spilled on the chemistry counter, calculate the mass of sodium bicarbonate needed to neutralize the acid

### Chemistry

If air is 20% oxygen, and the reaction is 2C2H2 + 5O2 --> 4CO2 + 2H2O, What volume of oxygen would be needed to completely burn 1.00 L of acetylene (C2H2)? I got 2.50 L but I'm not sure it's right. What volume of air would be needed to completely burn 1.00 L of acetylene ...

### Chemistry

Compare the energy needed to raise the temperature of 1kg of water from 20°C to 100°C and the energy needed to boil 1kg of water at 100°C? I turned 1kg to 1000g water is 4.18J/g°C and subtracted 20°C then i get confused as what to do next to

### Chemistry

Can someone please check my work? Calculate the mass of (NH4)2S2O8 needed to prepare 250mL of a 0.100M solution. I got 5.705 g. Calculate the volume of 2.00M KI needed to prepare 250mL of a 0.200M solution. I got 0.025L or 25mL. Calculate the volume of 0.100M Na2S2O3 needed to...

### chemistry

how many gram of h2 needed to react with 3.10 n2

### chemistry

how many gram of h2 needed to react with 3.10 n2

### Chemistry

How many mL of 1.2 M HCl is needed to react with 5.8 g of Al(OH)3

### Chemistry

A solution contains 1.694 mg of CoSO4 (MW 155.0) per mL. Calculate a) The volume of 0.008640 M EDTA needed to titrate a 25.00 ml aliquot of this solution. Step 1. 0.001694g * 25ml * 1/155 g/mol= 0.0002732 mol Step 2. Volume of EDTA needed = 0.0002732 mol/ 0.008640 M = 0.03125 ...

### Chemistry

A chemist wants to make 500.0 mL of 0.215M NaCl. What mass of NaCl is needed? would it be .500 L x .215 M = .1075 mol NaCl .1075 mol x 58.44g NaCl = 6.28g NaCl needed

### Organic Chemistry

I am suppose to calculate the theoretical amount (volume) of 3M sodium hydroxide needed to convert 1.5 g of benzoic acid to its salt. Also calculate the volume of 12M HCl needed to convert the sodium benzoate back to benzoic acid. how do I go about doing this? Thanks

### chemistry

1. calculate the volume of concentrated HNO_3 (68%)that is needed to prepare stock solution 0.25M in 1000mL volumetric flask. (density HNO_3 = 1.513 g/cm^3) 2. from above stock solution, determine volume needed to dilute to 500mL volumetric flask that contained 10 times dilution.

### Chemistry

1. calculate the volume of concentrated HNO3 (68%)that is needed to prepare stock solution 0.25M in 1000mL volumetric flask. (density HNO3 = 1.513 g/cm^3) 2. from above stock solution, determine volume needed to dilute to 500mL volumetric flask that contained 10 times dilution.

### Chemistry

How are the two parts of a conversion factor related? Either the numerator or the denominator is one of the units needed for the converstion, then the denominator/numerator is the other unit needed. thanks. whats two conversion factors based on the relationship between hours ...

### Chemistry

Hello, I was hoping that I could get some help with calculating the mass needed to completely react with this question. In the following chemical reaction between H2 and N2 to produce NH3, what is the mass of N2 needed to completely react with 0.65 g H2 to produce 3.68 g of ...

### chemistry

How many mL of 0.3 M HCl(aq) are needed to neutralize a 60 mL solution of 0.15 M Ba(OH)2?

### chemistry

what volume of O2 at STP is needed to react with 4.52 g of K

### chemistry

How many grams of N2 are needed to react with 125g of H2?

### chemistry

How many moles of are needed to react with 0.460 ?

### Chemistry

Calculate the mass of Mg needed to produce ~40 mL of H2. how do I do this?

### AP Chemistry

To eject electrons from the surface of potassium metal, 222kJ/mol of electrons are needed. a) What minimum frequency of light is needed to supply the required energy? b) What is the wavelength of this light? c) If potassium is irradiated with light having wavelength of 350 nm...

### physics multiple choice

A force F is required to push a crate along a rough horizontal floor at a constant speed V with friction present. What force is needed to push this crate along the same floor at a constant speed 3V if friction is the same as before? A. A constant force 3F is needed. B. A force...

### physics multiple choice

A force F is required to push a crate along a rough horizontal floor at a constant speed V with friction present. What force is needed to push this crate along the same floor at a constant speed 3V if friction is the same as before? A. A constant force 3F is needed. B. A force...

### chemistry

Phosphorus pentachloride, PCl5, reacts with water to form phosphoric acid, H3PO4, and hydrochloric acid, HCl. PCl5(s) + 4H2O() → H3PO4(aq) + 5HCl(aq) (a) What mass of PCl5 is needed to react with an excess quantity of H2O to produce 23.5 g of H3PO4? (b) How many ...

### Chemistry

the number of moles of O2 needed to produce 14.2g of P4O10 from P?

### chemistry

how many grams of H are needed to produce 1.80grams of H2O

### chemistry

what is the energy needed to melt 5.62 moes of ice in 0'C

### chemistry

if i want to change the pH of any solution from 5 to 8 what the volume of NaOH 0.1 N needed

### chemistry

how many mL of 0.50 M ammonia would be needed to react with 1.0 L of 0.75 M HClO4

### Chemistry

how many moles of o2 are needed to produce 3.91 mol fe2o3

### chemistry

What mass of ZnCl2 is needed to make 4 L of 1.8 M solution?

### Chemistry

How many mL of 5.5 M KOH are needed to prepare 300 mL of 1.2 M NaOH?

### Chemistry

How many mL of .48 M NaOH are needed to react with 2.00 moles of H3PO4?

### chemistry

what is the mass of LiF is needed to produce 2.5 L of a .30 M solution

### Chemistry

How many grams of NaOh are needed to prepare 0.5l of a 4m solution?

### Chemistry

How many mole of KClO3 are needed to make 320g O2

### chemistry

How many grams of O2(g) are needed to completely burn 24.0 g of C3H8(g)?

### chemistry

How many grams of H2 are needed to produce 10.75g of NH3?

### Chemistry

How many grams of H2 are needed to produce 12.88g of NH3?

### chemistry

How much energy is needed to melt 25.4 grams od I2?

### chemistry

how many HCl needed to dissolve 1 grams of Al2O3.

### chemistry

How many grams of H2 are needed to produce 12.22g of NH3?

### Chemistry

how many L of O2 are needed to react completely with 63.0 L of H2S and STP?

### Chemistry

What is the mass needed to make 8.5L of a 4.0 M solutution of Na2SO4? (Na=23, s=32, O=16)