Chemical Reaction Rates: Factors and Catalysis
Chemical Reaction Rate
Experience indicates that the rate at which reactants are transformed into products varies greatly from one reaction to another. Some reactions are extremely slow, while others are almost instantaneous. The rate of a reaction is a positive quantity that expresses the change of concentration of a reactant or product over time.
Measuring the Rate of Reaction
The rate can be found at a particular moment, called the instantaneous rate. The rate of a reaction at a given instant is
Read MoreUnderstanding Chemical Changes and Thermodynamics
Understanding Chemical Changes
One change is the transformation of a system over time. Type: Physical change: No change of the material (mechanical, electricity, magnetism, chemical, …). Change: This involves a modified form and has associated energy changes. He studied chemistry and thermodynamics (thermochemistry). The matters that become known as the reagents and obtained products. The change is the process or chemical reaction.
Chemical Laws
Chemical rearrangement of atoms = Change = link restructuring
Read MoreUnderstanding Battery Types and Their Functions
BATTERIES
A battery is a series of electrolytic cells used to generate a continuous electrical current or direct current. There are primary cells and secondary cells. Commonly called primary cells or batteries, they produce electricity through an irreversible chemical process and, when depleted, must be removed and replaced. Secondary cells, commonly called accumulators, operate on a reversible principle and can be recharged by connecting them to an adequate source of electrical power.
Every cell
Read MoreUnderstanding Pure Substances and Thermodynamics Principles
Pure Substances
Heat Transfer Equations
Q1 = m * Cn * ΔT
m: mass of water
Cn: specific heat of ice
Q2 = m * Lf: heat of fusion (latent) for ice
Q3 = m * C * ΔTC: Heat sensible
C: 1 Kcal/Kg
Q4 = m * Lv: heat of vaporization (latent) for H2O
Lv: 540 Kcal/Kg
Lv: 970 BTU / LBM
Q5 = m * Cv * ΔT
Cv: 0.45 Kcal / Kg
Example Calculation
200 g of ice at -10 ºC to calculate the amount needed to transform 200 g of steam at 120 ºC. The external pressure is 760 mmHg. The specific heat of ice is 0.5 cal / g ºC and
Read MoreEssential Processes in Food Manufacturing and Safety
1) Bread Manufacturing
Understanding Combustion Emissions and Air Quality Impact
Combustion is a major source of air pollution emissions. The complete combustion of hydrocarbon fuel produces only CO2 and H2O as products, according to the following stoichiometry:
CH4 + 2 O2
CO2 + 2 H2O
a) Mass of air required for complete combustion of 500 kg of CH4, assuming O2 = 21% of air.
b) Mass of CO2 produced from the above combustion.
c) Calculate the mass of air required for combustion of 500 kg of benzene (C6H6).
a) Mass of O2 required =
Mass of air required = 2000/0.23 = 8696 kg
b) Mass
Read More