Topic 2 Lesson 3 Quiz Flashcards
What three things does a chemical equation tell you?
1.compounds/molecules involved
2.elements
3. reactants/products
A chemical formula combines the ____________________ of different elements to represent ____________________ .
symbols, compounds/molecules
What does the “2” represent in H2O ? ____________________
How many hydrogen atoms are in the molecule
What does it mean when there is no subscript? ____________________
There is only 1 atom
A chemical equation indicates the substances involved in a reaction (__________________) and the substances that are formed as a result of the reaction (____________________).
reactants, products
Reactants are found on the ________________ and the products are found on the _____________________.
left, right
What symbol joins the reactants and the products? ____________________
arrow
The number that appear in front of a molecule is called the ______________________, and it shows _____________________ of a reactant is needed to produce a specific product.
coefficient, how much
2NH3
The above molecule is called ammonia. What does the “2” and what does the “3” represent?
“2” ammonia molecules and “3” hydrogen atoms in ammonia
If reactants need to be heated in order for a chemical reaction to occur, does the heat source like a flame count as one of the reactants?
Nope
Only the substances that are ____________________ ____________________ in the reaction are shown in the equation.
chemically rearranged
Matter is neither ____________________ nor ____________________ .
created, destroyed
In chemical reactions, the mass of the reactants ____________________ the mass of the products.
equal
However the products may have very different ____________________ .
properties
When you have too much of one reactant, you can have ____________________ reactants that didn’t chemically react. But, again, the mass will not have changed.
leftover
What are the correct coefficients?
____Fe + ____ O2 —–) FeO3
4Fe + 3O2 ——) FeO3
An open system, like plants, appears to violate the Law of Conservation of Mass, but that’s because matter can ____________________ and ____________________ the system undetected. In the case of the plants, we can’t see the Carbon Dioxide that enters and exits but we know it must be happening because the plant is growing.
enter, escape
Closed systems are better for measuring the movement of _______ and to study the ________ that involve gas.
matter, reactions
Which type of system is preferred by scientists for studying?
Closed
There are ____________________ different types of chemical reactions.
3
Synthesis - Two or more elements or compounds ____________________ to make a more complex substance.
Example: magnesium combusting with oxygen to form magnesium oxide
2Mg + O2 → 2MgO
combine
Decomposition - Compounds break down into ____________________ products.
Example: hydrogen peroxide breaks down into simpler products.
2H2O2 → 2H2O + O2
similar
Replacement - When one element or compound replaces another two elements and ____________________ ____________________
Example: The potassium (K) and lead (Pb) switch places with each other.
2KI + Pb(NO3)2 → PbI2 + 2KNO3
trade places
