[ENG 201] Chemistry prelims Flashcards

GANADEN - M1.4, M1.5, and M2.1

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Mass Percentage

Amount of mass of an element from a given compound

Mass Percentage

What formula is on the image:

Empirical Formula ( or Simplest formula)

Simplest elemental ratio in a compound. The formula of a substance written with the smallest integer (whole number) subscripts.

Molecular Formula

Actual number of elements in a compound

CH

What is the empirical formula of acetylene (C₂H₂)?

Stoichiometry

The calculation of the quantities of reactants and products involved in a chemical reaction

g B

(molar mass of B, written as mol B / g B or its inverse, depending on arrangement)

ANALYZE: In a typical stoichiometry problem, what step is missing in the sequence below?

grams of A × (g A / mol A) × (mol A / mol B) × (mol B / ?) = grams of B

Limiting Reactant

Reactant that gets used up first

Excess Reactant

Reactant that is supplied in excess

Limiting Reactant

The reactant that is entirely consumed when a reaction goes to completion.

Excess Reactant

A reactant that is not completely consumed

2 bowls and 1 excess grape

ANALYZE: If it takes 2 grapes and 1 pear to make 1 fruit bowl, how many fruit bowls can be made from 5 grapes and 2 pears, and how many grapes will be left as excess?

Percent Yield

How much product are actually formed

Dimensional Analysis

The method of calculation in which one carries along the units for quantities.

3,600 seconds

ANALYZE: Using dimensional analysis, how many seconds are there in 1 hour?

25 m/s

ANALYZE: Using dimensional analysis, convert a speed of 90 km/h into m/s.

2 m³/s × (1,000 L / 1 m³) × (60 s / 1 min) = 120,000 L/min

ANALYZE: Convert a flow rate of 2 m³/s to L/min using dimensional analysis

Thermochemistry

The study of heat change in a chemical reaction

Energy

The ability to do work

Potential Energy

Stored energy

Kinetic Energy

Energy exerted upon motion

Law of Conservation of Energy

Energy is neither created nor destroyed, but rather transformed into a different form.

Heat

The transfer of thermal energy between two bodies of different temperatures.

Law of Conservation of Energy

What law include windmills where the energy produced by the wind is transformed into electrical energy to power factories, etc.

System

A part or portion of the universe where the attention or reaction is focused on

Done BY the system

System that is indicated by a negative sign. It states that the heat from the system has been transferred to the surroundings.

Done ON the system

System that is indicated by a positive sign. It states that heat has been transferred from the surroundings into the system.

Surroundings

The rest of the universe other than the system.

Open System

TYPE OF SYSTEM: Heat inside and outside of the system could freely flow inside and out.

Closed System

TYPE OF SYSTEM: Heat flow inside and outside of the system is limited.

Isolated System

TYPE OF SYSTEM: Heat cannot escape the system

Endothermic

Heat is absorbed during a chemical reaction.

Exothermic

Heat is released during a chemical reaction.

Latent Heat

Energy that is absorbed or released during a phase change

Sensible Heat

The heat used or needed to raise the temperature of a substance.

Potential Energy Formula

= mgh

Kinetic Energy Formula

= ½ mv²

1 kgm²/s²

UNITS: 1 Joule = ?

4.184 J

UNITS: 1 cal = ? in Joules

1055 J

1 BTU = ? in Joules

END OF M1.4, M1.5, and M2.1

AGDA- M2.2-M2.3

First Law of Thermodynamics

• It states that energy is neither created nor destroyed, but rather transformed from form into another.

• The energy of the system plus the energy of the surroundings remain constant signifying energy conservation.

Thermal Equilibrium (Zeroth Law of Thermodynamics)

• States that when two bodies of different temperatures are next to each other and heat is transferred, the temperature will remain constant once equilibrium is reached, highlighting that the two bodies are of the same temperature.

Heat Capacity

• The temperature change is directly proportional to the amount of heat absorbed.

• The amount of energy needed to raise the temperature of a substance by 1 degree Celsius.

• It depends on the size and composition of the sample.

• It is directly proportional to the mass of the sample.

Specific Heat Capacity

• The amount of heat required to raise the temperature of a substance by 1 degree Celsius.

• It is not dependent on the mass.

Calorimetry

Measurement of heat changes in physical and chemical processes.

Constant Pressure Calorimetry

• Energy may be transferred as heat and as expansion work.

• A coffee cup calorimeter is a particular example where heat is transferred at a constant pressure.

• The heat transfer is equal to the change in enthalpy since the heat lost in the reaction is equal to the energy absorbed by the system.

Constant Volume Calorimetry

• Also known as “bomb calorimetry” where the volume remains constant during a chemical reaction.

• It measures internal energy change through ignition of a high pressure “bomb” submerged in water. 

• No work is done by the system as the volume is held constant.

End of M2.2-2.3