Chem Statements Flashcards
KMT theory basic ideas
- All matter is composed of extremely small particles that are in constant, rapid, random motion.
- Particle movement is driven by energy and collisions
- Temperature is related to the speed of the particles and pressure is measure of the force of the collisions of particles
- We assume that there are no attractive or repulsive forces between gas particles and collisions don’t cause a loss in energy.
Pressure
Pressure comes from collisions with the sides of the container/measuring device. To change pressure, the force/intensity or frequency of collisions must change
Temperature
- A measure of how fast particles are moving.
- An increase in temp indicates faster particle motion
Volume
The space particles can move in. Particle size is considered extremely small compared to the volume, so the space is viewed as empty
Amount
The number of particle groups. This may be measured in grams, particles, groups, puffs, units, etc
-Do not confuse the space (volume) with the number of particles (amount)
How do particle diffuse through a medium
As one type of particles move through another type of particles, collisions occur. These collisions cause the introduced particles (such as dye) to change their direction and speed. Continued collisions move the new particles throughout the original substance
Explain the process that causes the level of a thermometer to drop when it is placed in ice water
Thermometer is places in ice water, which transfers a small amount of energy to the water and the particles in the thermometer slow down
- This causes collisions inside the thermometer to be fewer and less intense
- Particles in the thermometer can then stay closer together causing the level of liquid to drop
How does a straw work
We suck in air particles and decrease the pressure in your mouth. The liquid in the glass is then pushed up the straw because the pressure pushing on the surface in the glass (atmospheric pressure) is greater than the pressure inside the straw. The greater force of the collisions on the surface will cause movement up against gravity.
Why does liquid stay in a straw when you put your finger over the end
In closing the top of the straw you create a close system of gas inside the top of the straw. The pressure on the top of the liquid is equal to the pressure below the straw. At typical atmospheric pressure, air pressure is sufficient to support a column of water up to 10m tall, so as long as the gas at the top of the straw remains trapped the outer air particles will keep pushing the water to remain in the straw, and the volume/pressure of the trapped air will remain constant.
Why increasing the amount of gas will increase the volume of a flexible container
-As more gas particles are introduced into a container the number of collisions with the inside of the container walls will increase, but the outside pressure is unchanged. The walls of the container will be pushed outward by the added collisions until the container is large enough where the number of collisions outside equals the number of collisions inside (external pressure equals internal pressure)
Why does increasing the temperature of a balloon cause the balloon to grow larger
As the temperature is increased, particles move faster, so they strike the sides of the balloon with greater force. This pushes out the sides of the balloon until the force pushing in on the balloon (external pressure) equals the force pushing outward (internal pressure)
What does STP stand for
Standard temperature and pressure
For what do you not use sig figs for
- STP (0 degrees Celsius and 273 kelvin and 1 atm)
- 760 torr
- 760mmHg
- 1 atm
If pressure in two different sized containers (volume) is the same how do you show it
-More pressure events in the larger container because more collisions over a larger area equals the same pressure
Sig figs 0s
They don’t count if they are at the beginning of the number and they do if they are at the end and there is a decimal point
