group iv cation analysis جداسازی کاتیون های گروه 4 valdosta state university...

Group IV Cation Analysisگروه های کاتیون 4جداسازی

Valdosta State University

Purposeهدف

To determine which group IV ions are present in an unknown solution.

گروه های کاتیون که است این ما محلول 4مقصود یک در موجودکنیم شناسایی را مجهول


Background

• For this experiment,we need the group IV ions that are: Na+, K+, Ba2+, Ca2+, Mg2+.

• گروه های کاتیون به ما آزمایش این عبارت 4برای که داریم نیازسدیم،پتاسیم،باریم،کلسیم،منیزیم از اند

• These are ions which are left after groups I – III have precipitated.

• گروه های تا 4یون یک گروه از بعد چپ سمت در هستند 3کهمیدهند رسوب


Group IV Unknown

BaCrO4

yellow ppt.

Flame Test Na+

orange-yellow flame

Ca2+, Mg2+

HC2H3O2, K2CrO4

Ba2+ Flame Testapple - green

BaSO4

white ppt.

6M HCl

6M H2SO4

CaC2O4

white ppt.Mg2+

MgNH4PO46H2Owhite ppt.

(NH4)2C2O4

NH3(aq), NaH2PO4, heat

Flame Testred-orange

6M HCl

Flame Test K+

lavender flame

Background – Group IV Separation Schemeگروه های کاتیون جداسازی 4نقشه


Group IV Unknown

Flame Test K+

lavender flameFlame Test Na+

orange-yellow flameA – Flame test for Na+ and K+

پتاسیم و سدیم شناسایی برای شعله تستنات پتاسیم و سدیم های نمک از محلولی

در معلومداریم اختیار

ها یون این وجود تععین برای روش یکاست شعله آزمون


K

HC2H3O2,K2CrO4

BaCrO4

yellow ppt.

Ba2+

6M HCl

Flame Testapple - green

BaSO4

white ppt.

6M H2SO4

B – Test for Ba2+

• The formation of a yellow precipitate on the addition of potassium chromate indicates the presence of the barium ion.

زرد رسوب کرومات پتاسیم کردن اضافه باوجود دهنده نشان که میشود تشکیل رنگی

است باریم .یون

Ba2+(aq) + K2CrO4(aq) BaCrO4(s) + 2K+(aq)


• A flame test (apple green) is used to confirm the presence of the ion.

• درمی سبزرنگ سیب رنگ به که شعله تستمیرود کار به یون این وجود تائید برای .آید

Ba2+(aq) + H2SO4(aq) BaSO4(s) + 2H+(aq)

سفید رسوب نوعی باریم برای نهایی تستاز محلولی کردن اضافه با که است رنگ

آید می دست به سولفات


Ca2+, Mg2+

CaC2O4

(NH4)2C2O4

Mg2+

Flame testred-orange

6M HCl

C – Test for Ca2+

• The calcium ion is separated from magnesium by precipitating calcium oxalate.

Ca2+(aq) + (NH4)2C2O4(aq) CaC2O4(s) + 2NH4+(aq)

Valdosta State UniversityValdosta State University

C – Test for Ca2+

• A flame test (red-orange flame) is used to confirm the presence of the calcium ion.

Ca2+, Mg2+

CaC2O4

(NH4)2C2O4

Mg2+


6M HCl

Valdosta State UniversityValdosta State University

C – Test for Mg2+

• The magnesium ion is precipitated as a white solid (ammonium phosphate) in an alkaline solution.

Ca2+, Mg2+

CaC2O4

K2C2O4

Mg2+


6M HCl

Mg2+(aq) + NH3(aq) + HPO42-(aq) MgNH4PO4(s)

MgNH4PO4–6H2Owhite ppt.

NH3(aq)Na2HPO4(aq)

Procedure – Experiment 12

- For this experiment, work individually.

Procedure – Group IV Separation Scheme


A – Flame test for Na+ and K+

1. Heat 2 mL of a Group IV cation known or unknown in an evaporating dish until a moist residue remains.

2. Add 20 drops of 6 M HCl to this moist residue, and again heat in the evaporating dish until a moist residue remains.

3. While the moist residue cools, obtain a piece of Nichrome wire and make a small loop in the end of the wire.

4. Clean the wire by dipping the loop in concentrated (12 M) HCl, and inserting the wire into the hottest part of the flame.

5. Keep the wire in the flame until the wire imparts no color to the flame.

Group IV Unknown

Flame Test Na+

orange-yellow flameFlame Test K+

lavender flame



A – Flame test for Na+ and K+

6. Dip the loop of the wire in the moist residue.

7. Place the loop of the wire in the flame and observe the color of the flame. A brilliant orange-yellow flame that persists is a positive test for sodium ion.

8. Clean the wire (steps 4, 5) 9. Dip the wire into the moist residue, and

insert the loop end of the wire into the hottest part of the flame. Observe the flame through a cobalt blue filter.

10.A lavender flame observed through the cobalt blue filter confirms potassium ion

Group IV Unknown

Flame Test Na+

orange-yellow flameFlame Test K+

lavender flame



B – Test for Ba2+

1. Obtain 2 mL of fresh Group IV cation known (or unknown) solution in a medium test tube and add 2 drops of 2 M NH4C2H3O2 and 1 drop of 6 M HC2H3O2.

2. Add 1 drop of 1 M K2CrO4 to the sample.3. A yellow precipitate means that barium

ion is likely to be present. 4. Centrifuge the solution and decant. 5. Save the decantate for Part C.

HC2H3O2,K2CrO4

BaCrO4

yellow ppt.

Ba2+

6M HCl


BaSO4

white ppt.

6M H2SO4



B – Test for Ba2+

6. To the precipitate, add 6 M HCl dropwise until the precipitate dissolves, then add 10 more drops.

7. Transfer 5 drops of the solution to an evaporating dish, and heat until a moist residue remains. Perform a flame test on the moist residue.

8. A weak, apple-green flame is also an indication that barium ion is present.

9. To the remainder of the solution, add 10 drops 6 M H2SO4.

10.A white precipitate also indicates barium ion.

HC2H3O2,K2CrO4

BaCrO4

yellow ppt.

Ba2+

6M HCl


BaSO4

white ppt.

6M H2SO4



C – Test for Ca2+

1. Add 6 M NH3 to the supernatant from Part B until the solution is basic to litmus.

2. Add 10 drops of saturated (NH4)2C2O4 and stir.

3. A white precipitate indicates the presence of calcium ion.

4. If no precipitate appears immediately, warm the solution in a water bath.

5. If a precipitate forms, centrifuge and decant.

6. Save the decantate for Part D.

Ca2+, Mg2+

CaC2O4

(NH4)2C2O4

Mg2+


6M HCl



C – Test for Ca2+

7. Add 6 M HCl to the white precipitate until it dissolves, then add 10 more drops.

8. Transfer the solution to an evaporating dish and heat until a moist residue remains.

9. Perform a flame test on the moist residue,

10.A fleeting red-orange flame is an indication that calcium is present.

Ca2+, Mg2+

CaC2O4

(NH4)2C2O4

Mg2+


6M HCl



D – Test for Mg2+

1. If the decantate from Part C is not basic, add 6 M NH3 until the solution is basic to litmus, then add 5 drops more.

2. Add 10 drops 1 M Na2HPO4 and set the solution aside for approximately ten minutes.

3. A white, crystalline precipitate of MgNH4PO4 (looks like snow) confirms the presence of magnesium.

Ca2+, Mg2+

CaC2O4

(NH4)2C2O4

Mg2+


6M HCl

MgNH4PO4–6H2Owhite ppt.

NH3(aq)Na2HPO4(aq)

Safety


• Concentrated HCl causes severe burns to the skin which can take weeks to completely heal and also can cause serious eye damage. This chemical also destroys books and clothing. If you get any on you, wash the affected area(s) with copious quantities of water for ten minutes.

• Other 6 M acids can cause burns. If you spill some on your skin, wash the affected area with water for five minutes.

Waste Disposal

Because the solutions used in this experiment contain ions that can hazardous to the environment and to human health, all solutions and precipitates used in this experiment must be placed in the container marked "Recovered Metals and Metal Ions".


group iv cation analysis جداسازی کاتیون های گروه 4 valdosta state university...

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