1.i state of matter a physical change or a chemical change
2.why does heat go to coldest to hottest change?
3.what type of phase change occur when a substance change to solid to gas
4.what is an ex of sublimation
See your post just above.
1. Determining whether a state of matter change is a physical change or a chemical change requires understanding the difference between the two. A physical change refers to a change in the physical properties of a substance, such as a change in shape, size, or state of matter (solid, liquid, gas) without altering the chemical composition of the substance. On the other hand, a chemical change involves a transformation in the chemical composition of a substance, resulting in the formation of one or more new substances with different properties.
To determine if a state of matter change is a physical or a chemical change, you need to consider whether the change alters the chemical structure of the substance or merely its physical appearance. If the change only involves a conversion between different states of matter (e.g., solid to liquid, liquid to gas), without any alteration to the chemical composition or structure, then it is a physical change.
2. Heat always flows from a higher temperature region to a lower temperature region, following the principle of the Second Law of Thermodynamics. This natural flow of heat occurs due to the concept of thermal equilibrium. When two objects of different temperatures come into contact, the hotter object transfers thermal energy to the colder object, resulting in a transfer of heat. This continues until both objects reach the same temperature and achieve thermal equilibrium.
The driving force behind this heat transfer is the tendency for systems to move towards a state of equilibrium, which represents a balance in energy distribution. Heat energy naturally flows from hotter objects to colder objects to equalize the energy distribution, with the goal of reaching a state of equilibrium where there is no net flow of heat. This process is known as thermal equilibration.
3. The phase change that occurs when a substance changes from a solid to a gas is called sublimation. Sublimation is a phase transition where a solid substance bypasses the liquid phase and directly transitions into a gas when heated. This occurs when the vapor pressure of the solid exceeds the environmental pressure.
During sublimation, the solid particles gain enough energy to overcome the attractive forces that hold them in the solid state. As a result, they transform into a gas without passing through the liquid phase. Examples of substances that undergo sublimation include dry ice (solid carbon dioxide) and mothballs (solid naphthalene).
4. An example of sublimation is the process of dry ice subliming. Dry ice is the solid form of carbon dioxide (CO2) and sublimes at a temperature of -78.5 degrees Celsius (-109.3 degrees Fahrenheit) under normal atmospheric conditions. When exposed to air, dry ice directly converts from a solid to a gas without melting into a liquid. This sublimation process can be observed by witnessing the solid dry ice gradually transforming into a gaseous form and releasing "smoke-like" carbon dioxide gas.