1 / 18

SURVEY OF CHEMISTRY LABORATORY I CHEM 1151L DETERMINATION OF ATMOSPHERIC PRESSURE

SURVEY OF CHEMISTRY LABORATORY I CHEM 1151L DETERMINATION OF ATMOSPHERIC PRESSURE. CAUTION!!!. BE SURE TO WEAR SAFETY GLASSES AT ALL TIMES IN THE LABORATORY NO EXCEPTIONS TO THIS RULE!. DETERMINATION OF ATMOSPHERIC PRESSURE.

kentl
Download Presentation

SURVEY OF CHEMISTRY LABORATORY I CHEM 1151L DETERMINATION OF ATMOSPHERIC PRESSURE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SURVEY OF CHEMISTRY LABORATORY I CHEM 1151L DETERMINATION OF ATMOSPHERIC PRESSURE

  2. CAUTION!!! BE SURE TO WEAR SAFETY GLASSES AT ALL TIMES IN THE LABORATORY NO EXCEPTIONS TO THIS RULE!

  3. DETERMINATION OF ATMOSPHERIC PRESSURE - To form and collect a sample of hydrogen (H2) gas through a chemical reaction - Students will measure the volume of hydrogen gas - Students will use the room temperature and the calculated moles of the H2 gas to determine the atmospheric pressure

  4. DETERMINATION OF ATMOSPHERIC PRESSURE - The pressure of the gas is the total pressure of all gases present - Hydrogen gas is collected over water so contains some water vapor - Ideal gas relationship will give pressure due to the H2 gas only - Water vapor pressure can be determined using room temperature and Table 1 Atmospheric Pressure = calculated H2 pressure + water vapor pressure

  5. THE IDEAL GAS LAW PV = nRT P = pressure of a gas (1 atmosphere = 760 mm Hg) V = volume of the gas expressed in liters (L) n = moles of the gaseous substance T = temperature of the gas in Kelvin (K = ˚C + 273) R = gas constant

  6. MAGNESIUM METAL - Mass a piece of magnesium (Mg)metal - Make sure the mass is between 0.030 g and 0.050 g - Record the mass

  7. MAGNESIUM METAL - Bend the Mg metal strip - Wrap some copper wool loosely around the Mg metal - Tie the bundle securely with about 2-3 ft of string

  8. OBTAIN BEAKER AND STAND - Obtain a ring stand and a buret clamp - Also obtain a 1000 mL beaker - Fill the beaker with water (about half-filled) - Set them aside

  9. FILL TUBE WITH HCl - Using the dispensing bottle - Dispense about 10 mL of 12 M hydrochloric acid (HCl) directly into a gas collection tube

  10. FILL WITH WATER AND SUBMERGE SAMPLE - Carefully and quickly fill the rest of the tube with distilled water - Avoid mixing Click on picture to play video

  11. FILL WITH WATER AND SUBMERGE SAMPLE - Submerge the metal sample in the tube to the 50 mL mark - Completely fill the tube

  12. IMMERSE TUBE IN BEAKER - Cover the tube opening with your finger and invert the tube - Immediately insert the tube into the beaker of water - Take finger off when the tube is completely immersed in the water - Place the gas tube in the buret holder clamp and adjust the gas tube so it is just touching the bottom of the beaker

  13. H2 GAS EVOLES Mg + 2HCl → MgCl2 + H2 - The HCl will move slowly down the tube - HCl will react with Mg upon contact - H2 gas will be evolved and trapped in the tube - Equal volume of water will be displaced by the H2 gas - Make sure no gas escapes from the tube Click on picture to play video

  14. REACTION GOES TO COMPLETION - No more gas bubbles will be given off when reaction is complete - That is Mg is completely used up - Tap the tube to dislodge any clinging gas bubbles

  15. MEASURE VOLUME OF H2 GAS - Unclamp the gas tube and lift slightly (open end still under water) - Cover the open end with your finger and remove from the beaker - Gas collection tube should remain in the inverted position

  16. MEASURE VOLUME OF H2 GAS - Transfer tube to a large graduated cylinder filled with water - Remove your finger once the end of the tube is under water - Immerse the gas tube until the liquid level in the gas tube is even with the liquid level in the large container - Read and record the volume of the hydrogen gas (in mL) from the gas collection tube

  17. MEASURE ROOM TEMPERATURE - Measure and record the room temperature (in oC) around the time volume measurement is taken - Do not hold thermometer by the bulb - Use the temperature to determine the water vapor pressure from Table 1 in the manual

  18. COMPLETE CALCULATIONS AND CLEAN UP - Remove and dispose of the copper wadding - Complete all calculations

More Related