4.1- Writing and Balancing Chemical Equations - The Magic of Chemistry Flashcards
What aspects of a chemical substance does a physical change affect?
It’s form, but not its composition (doesn’t make new substances).
What is the most common physical change?
Changes of state.
Name three physical changes other than changes of state:
- Dissolution
- Ferromagnetism
- Tempering
What do you call it when a solute dissolving in a solvent still reforms when you remove the solvent?
Dissolution.
What do you call it when a material forms a permanent magnet without changing chemical composition?
Ferromagnetism
What do you call it when the toughness of iron-based alloys is increased allowing them to better deform without breaking?
Tempering.
What is the difference between liquid state and aqueous solution?
A substance is only in the liquid state if it melted from solid.
What do you call the starting materials that react during a chemical reaction?
Reactants.
What do you call the new materials formed by the chemical reaction?
Products.
What is evidence that a chemical reaction took place?
- The reaction absorbed or released energy.
- Change of colour.
- Gas forms (bubbles)
- One of the products is solid and sinks to bottom of container.
What do you call an insoluble solid that forms from the reaction of two transparent aqueous solutions?
Precipitate.
If the precipitate of a solution remains suspended, what is the solution?
A colloid.
If the precipitate of a solution sinks to bottom, what is the solution?
A suspension.
What is a system that does not allow anything to enter or leave?
Closed system.
What is a system that allows things to enter or leave?
Open system.
What do you call the law that says in a closed system, total mass does not change?
Law of conservation of mass.
If mass is conserved during a chemical change, what other things must therefore be conserved?
- Atoms
- Charge
- Energy
What law says in a closed system, the total number and type of atoms does not change during a chemical reaction?
Conservation of atoms.
What law says that in a closed system, the total electrical charge does not change during a chem reaction?
Conservation of charge
What law says in a closed system, the total amount of energy doesn’t change?
Conservation of energy.
A balanced equation ensures what?
The conservation of mass, atoms and electrical charges.
Why is conservation of energy nearly impossible in a chemical reaction?
No one has yet prevented all energy transfer.
What do you call the numbers written before the formula of each reactant and product representing how many particles of each element are present?
Coefficients.
What are the simple steps of balancing an equation?
- Count elements on each side
- Determing which need to be balanced
- Simpler first
- Leave H O and H2O until end.
- Save lone elements for the end.
- Start with metal.
- To change from odd to even, double all elements.
