CO₂ và Thử Nghiệm Nước Vôi
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Nhận biết khí cacbon dioxit bằng canxi hydroxit
Mục tiêu
Tạo khí cacbon dioxit từ phản ứng cacbonat-axit và xác nhận danh tính bằng thử nghiệm nước vôi.
Bối cảnh
When baking soda (sodium bicarbonate) reacts with vinegar (acetic acid), CO₂ gas is produced. Bubbling this gas through limewater (calcium hydroxide solution) produces a characteristic white milky precipitate of calcium carbonate, confirming the presence of CO₂.
Cảnh báo an toàn
- Limewater is mildly irritating — avoid eye contact
- CO₂ is an asphyxiant in large quantities — work in ventilated area
PPE cần thiết
Vật liệu
-
Baking soda (NaHCO₃) (10 g)
-
White vinegar (50 mL)5% acetic acid
-
Limewater (Ca(OH)₂ solution) (100 mL)Clear, saturated
Thiết bị
Quy trình
Pour 100 mL of clear limewater into a test tube or small beaker.
Place 10 g of baking soda in the Erlenmeyer flask.
Add 50 mL of vinegar to the flask. Quickly insert the stopper with delivery tube.
Direct the delivery tube into the limewater. Bubble the CO₂ through for 2-3 minutes.
Observe the limewater turning milky white as calcium carbonate precipitate forms.
Continue bubbling. If enough CO₂ passes through, the solution may turn clear again as soluble Ca(HCO₃)₂ forms.
Kết quả dự kiến
The clear limewater turns milky white due to CaCO₃ precipitation: Ca(OH)₂ + CO₂ → CaCO₃ + H₂O. With excess CO₂, the milkiness clears: CaCO₃ + CO₂ + H₂O → Ca(HCO₃)₂.
Dọn dẹp
Neutralize remaining vinegar solution. Dispose of limewater down the drain. Rinse all equipment.
Chi tiết
- Danh mục
- Gas Laws
- Độ khó
- Beginner (Middle School)
- Thời gian
- 20 phút
- Chi phí ước tính
- $5,00
- Số bước
- 6
- Vật liệu
- 3