Unit 4 Chemical Reactions Lesson 1 Chemical Equations

Unit 4: Chemical Reactions Lesson 1: Chemical Equations and the Conservation Laws

Chemical Equations Reactants Products 2 Na + Cl 2 → 2 Na. Cl Coefficients Subscript

Closed and Open Systems • A system is the part of the universe being studied in a particular situation. • A system is closed if nothing can enter or leave it. • A system is open if things can enter and leave it.

Think-Pair-Share! Give an example of a system that is. . . • Closed with respect to light. • Open with respect to light but closed with respect to mass. • Closed with respect to sound. • Open with respect to mass and closed with respect to light. • Closed with respect to heat.

Conservation Laws • A quantity is conserved if it does not change during a chemical reaction. • There are four quantities that are conserved in all chemical reactions, giving us four “conservation laws” that can’t be broken. • Predict: What do you think these four quantities might be? Write down your prediction!

Brain Break!

Conservation Laws • Observe: Is there a conservation law for. . . a) Mass? b) Volume? c) Atoms?

Conservation Laws • Chemical reactions obey the laws of conservation of. . . 1) Mass 2) Atoms 3) Charge 4) Energy • These four quantities do not change during a chemical reaction in a closed system.

Homework: • Pg. 107 #4