# CHEM AB HELP ASAP

I have a pre lab questions that are due in a few hours and I need help. Theres several questions

In the titration of 25.00 ml of a water sample, it took 20.590 ml of 4.995x10-3 M EDTA solution to reach the endpoint.

The total hardness is due to one or a combination of Ca2+, Mg2+, and Fe2+ in your sample. It is convenient to express this hardness as though it was entirely due to Ca2+. Making this assumption, determine the number of moles of Ca2+ present in the bottled water sample titrated.
The total hardness is always listed in parts-per-million (ppm) of CaCO3 (or mg CaCO3 / Kg H2O). Since the density of water is 1.0 g/ml, one ppm would be the same as the number of mg of CaCO3 per liter of water. Determine the number of moles of CaCO3 present in the titrated sample of water, assuming that all the Ca2+ combines with CO32−.

Calculate the number of grams of CaCO3 present and convert to mg.

Convert the number of ml of bottled water used in eache sample titration to Liters.

Calculate the ppm of CaCO3 = mg CaCO3 / Liters H2O used.

1. 👍
2. 👎
3. 👁
1. mols EDTA = M x L = ?
mols Ca^2+ = same as mols EDTA

g CaCO3 = mols x molar mass CaCO3. That's g CaCO3 in 25.00 mL.
Convert that to mg/L for ppm CaCO3.

1. 👍
2. 👎

## Similar Questions

1. ### pre-algebra

The number of cells in a lab sample triples every 4 hours. Write an expression to represent the number of cells after 24 hours. I think it might be x cubed times 6

2. ### Chem Urgent Help ?

I have a lab dis monday .. plz someone help .. Lab Title is (( Recrystallization of a Solid )) Pre-Lab Questions.... Explain the purpose of the following in this experiment. a) using hot filtration b) not cooling (chilling) the

3. ### Physics

A bus travels 80 km due south in 2 hours it then travels 100 km due west in 3 hours what is the average velocity of the bus

4. ### Chem

Can someone help with this one? Half life of 55Cr is about 2 hours. A sample of the isotopes delivered from the reactor to lab requires 12 hours. What is the minimum amount of material that should be shipped to get 1.0 mg of 55Cr.

1. ### Mechanics

a ship leaves a port and travels on asteady course 40*N of due east at a steady speed of 8.kmh^-1. how far due north and due east of the port is the ship after sailing after 12 hours

2. ### Science 7R (Lab questions)

We did a lab today at science and for homework we have to answer questions about the Lab. I need help on 2. 12. Name two ways that a plant and animal cells differ in structure? 13. How are plant and animal cells different in

3. ### Physics 30

inquiry lab determining the refractive index of a variety of materials (Snell's Law Lab): Basically this lab: We us a polar coordinate paper and a semicircular shaped containers which we switch between, which are composed of

4. ### Chemistry: Bunsen Burner Lab

Hi! I have recently completed a bunsen burner lab and need help with a few conclusion questions: 1) What kind(s) of energy is released by the reaction of fuel and air in this system? 2) Which part of the Bunsen flame is hottest?

1. ### chemistry

hello, I have done a acid & base titration lab, with 0.1M vinegar (with unknown %tage acid) and 0.1 NaOH...I think the result came out ok, in avg, 25.21mL of NaOH have titrated w/ 30.0mL unknown %tage acid of vinegar. all I am

2. ### chem plzzz help

okay so im doing pre lab questions on reaction rates I have a chart labeled effects of varying concentration in reaction #1 flask A contains 7.50mL of .200 M KI , none of .20M KCI, 5.00 mL of .0050 M S2O3^2-, 1 drop of starch.

3. ### Physics

A plane flies due north (90° from east) with a velocity of 100 km/h for 3 hours. During this time, a steady wind blows southeast at 30 km/h at an angle of 315° from due east. After 3 hours, where will the plane’s position be

4. ### algebra

An airplane flies 750 miles due west in 1 1/2 hours and 750 miles due south in 2 hours. What is the average speed of the airplane?