Give a scientific explanation for the following observations. Use equations or diagrams if they are relevant.
A. burning coal containing a significant amount of sulfur leads to "acid rain".
B. Perspiring is a mechanism for cooling the body.
C. At room temperature, NH3 is a gas and H2O is a liquid, even though NH3 has a MM of 17 g/mol and H2O has a MM of 18 g/mol
D. C(graphite) is used as a lubricant, whereas C(diamond) is used as an abrasive.
for A. is it because the flame reacts with the sulfur in the coal to make acid rain instead of water?
What you say for A is correct but it misses the point a little. S burns to produce SO2 and SO3 and these gases then react with H2O to form H2SO4.
For B. Think heat of vaporization of water.
For C. Think hydrogen bonding.
For D. Think crystal structure.
for b.. is it because when something is heated it produces a salt and h2o, so when our body heats up the chemicals in our body let out salt and water, essentially combining to make perspiration. also, it helps to keep a balance in temperature in our body...
A. Burning coal containing a significant amount of sulfur leads to "acid rain":
To understand this observation scientifically, we need to know that sulfur dioxide (SO2) is released when coal containing sulfur is burned, and this gas can react with water in the atmosphere to form sulfuric acid (H2SO4). The chemical equation for this reaction is:
SO2 + H2O → H2SO4
The sulfuric acid that is formed can then dissolve in rainwater and fall to the ground as acid rain.
B. Perspiring is a mechanism for cooling the body:
When our body temperature rises due to physical activity or exposure to warm conditions, perspiration, also known as sweating, occurs. Perspiration helps to cool the body through the process of evaporation.
When sweat evaporates from the skin, it absorbs heat energy from the body, thus lowering the body temperature. The evaporation process requires energy, and the heat from the body is utilized for this purpose. This phenomenon is known as evaporative cooling.
C. At room temperature, NH3 is a gas and H2O is a liquid, even though NH3 has a molar mass (MM) of 17 g/mol and H2O has a MM of 18 g/mol:
The state of matter (solid, liquid, or gas) at a given temperature and pressure is influenced by intermolecular forces. In the case of ammonia (NH3) and water (H2O), although NH3 has a slightly lower molar mass, water exists as a liquid at room temperature while NH3 exists as a gas.
This discrepancy can be explained by examining the intermolecular forces present in each substance. Ammonia molecules are attracted to each other through weak hydrogen bonding, which is relatively weaker than the hydrogen bonding in water. Therefore, at room temperature, the kinetic energy of the NH3 molecules is sufficient to overcome these intermolecular forces and stay in the gaseous phase.
On the other hand, water molecules have stronger hydrogen bonding between them, leading to a higher boiling point and a liquid state at room temperature.
D. C(graphite) is used as a lubricant, whereas C(diamond) is used as an abrasive:
Graphite and diamond are two allotropic forms of carbon, with different structures and properties. Graphite is made up of hexagonal layers of carbon atoms whereas diamond has a three-dimensional, covalent network structure.
Graphite is an excellent lubricant because the carbon layers can easily slide past each other, due to weak interlayer forces. This sliding action reduces friction and allows smooth movement between two surfaces.
On the other hand, diamond has a very rigid and strong network structure held together by strong covalent bonds. This makes diamond extremely hard and resistant to wear. Therefore, it is used as an abrasive material for cutting, grinding, and polishing other materials.