Questions 4-6: Use the following Molar Masses: H2: 2.02 g/mol Oz: 32.00 g/mol H2O: 18.02 g/mol
5) What mass of oxygen is needed to completely react
with 32.0 g of hydrogen?
2 Hz O2 → 2 H2O
+
32 g H2
х
x
x
= 329 H2
= 1g 42
= 2.02 g H2
= 1 mol H2
* 2.02 mol H2
- 2 mol H2
# 1 mol O2
- 2 mol O2
# 32 mol Oz
3 32 mol O2
=> 32 g 02
- 1 g 02
= 1013 g 02
: 0.248 g 02
253.4 g 02

Mass =   253.4 g

Explanation:

Given data:

Mass of oxygen required = ?

Mass of hydrogen available = 32.0 g

Solution:

Chemical equation:

2H₂ + O₂     →       2H₂O

Number of moles of hydrogen:

Number of moles = mass/molar mass

Number of moles = 32.0 g/ 2.02 g/mol

Number of moles = 15.84 mol

Now we will compare the moles of hydrogen and oxygen:

                  H₂         :           O₂

                   2          :           1

              15.84        :         1/2×15.8 = 7.92 mol

Mass of oxygen required:

Mass = number of moles × molar mass

Mass = 7.92 mol × 32.00 g/mol

Mass =   253.4 g

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

answer; 4 electrons;