Carbon has 4 valence electrons so to gain a noble gas electron configuration, which has 8 valence electrons and is the most electrically stable, carbon needs 4 more electrons.
<span>Pre-1982 definition of STP: 37 g/mol
Post-1982 definition of STP: 38 g/mol
This problem is somewhat ambiguous because the definition of STP changed in 1982. Prior to 1982, the definition was 273.15 K at a pressure of 1 atmosphere (101325 Pascals). Since 1982, the definition is 273.15 K at a pressure of exactly 100000 Pascals). Because of those 2 different definitions, the volume of 1 mole of gas is either 22.414 Liters (pre 1982 definition), or 22.71098 liters (post 1982 definition). And finally, there's entirely too many text books out there that still use the 35 year obsolete definition. So let's solve this problem using both definitions and you need to pick the correct answer for the text book you're using.
First, determine how many moles of gas you have. Just simply divide the volume you have by the molar volume.
Pre-1982: 2.1 / 22.414 = 0.093691443 moles
Post-1982: 2.1 / 22.71098 = 0.092466287 moles
Now determine the molar mass. Simply divide the mass by the moles. So
Pre-1982: 3.5 g / 0.093691443 moles = 37.35666667 g/mol
Post-1982: 3.5 g / 0.092466287 moles = 37.85163333 g/mol
Finally, round to 2 significant figures. So
Pre-1982: 37 g/mol
Post-1982: 38 g/mol</span>
Answer:
In the 1H NMR spectrum of ethanol three different signals are observed, this is due to the existence of 3 types of hydrogens with different chemical environment. Hydrogens A (3.57 ppm) are more screened than C (1.10 ppm) due to the presence of oxygen (electonegative atom that removes electron density). The chemical environment of hydrogen B (4.78 ppm), attached directly to oxygen, is also different by resonating at a frequency different from the previous ones.
The hydroxylic hydrogen produces a singlet, the pair of carbon hydrogens one give rise to a quadruplet and the three hydrogens of carbon two produce a triplet.
Explanation:
Atmospheric pressure at sea level is 760 mmHg.
We have been told that at the summit the pressure is only one third the pressure at sea level.
Then the pressure at the mountain top is
mmHg
Air is made of a mixture of gases. the pressure that each gas exerts individually contributes to the total pressure of the system. The pressure that each gas exerts is the partial pressure of that gas which depends on the mole fraction of that gas or percentage composition of the individual gas.
Partial pressure of Oxygen - total pressure x percentage composition
Therefore pO₂ -
= 53.2 mmHg
Answer is 53 mmHg