Chemical Equations and Formulas
Law of Conservation of Mass
All chemical equations must be balanced. This means that the same number of atoms of each element must be found in both the reactants and the products of the reaction. Which scientific law does this illustrate?
36 grams
If 32 grams of oxygen are combined with 4 grams of hydrogen, how much water would be formed?
arrow
In a chemical equation the ________ symbol shows a reaction has take place.
True
In a chemical equation, the coefficients tell you the number of molecules of each reactant used and the number of molecules of each product made. - True - False
False
In a chemical equation, the reactants and products can have different numbers of atoms for each element. - True - False
False
In a chemical equation, you can end up with different numbers of atoms of an element on the reactant side for the same element on the product side. - True - False
products
In a chemical reaction the new substances formed are called the ________.
coefficient
In the chemical equation above what is letter "A" pointing to?
subscript
In the chemical equation above what is letter "B" pointing to?
chemical formula
In the chemical equation above what is letter "C" pointing to?
chemical symbol
In the chemical equation above what is letter "D" pointing to?
reactants
In the chemical equation above what is letter "E" pointing to?
products
In the chemical equation above what is letter "F" pointing to?
2
In the equation above, what is the coefficient of the oxygen molecule?
2
In the equation above, what is the subscript of the oxygen molecule?
1
In the table, how many atoms of oxygen are in hydronium?
Hydrogen Peroxide
In the table, what does H2O2 stand for?
Law of Conservation of Mass
In this law the number of atoms in the reactants must be equal to the number of atoms in the product.
chemical equation
Is this a chemical equation or a chemical formula?
balanced
Is this equation balanced or unbalanced? Hint: T-chart!
unbalanced
Is this equation balanced or unbalanced? Hint: T-chart!
18 degrees Celsius
Juan is conducting an experiment to see what occurs when a mystery substance is added to water. He measures out 250 ml of water in four beakers. Juan then measures out four different amounts of the mystery substance (4g, 8g, 12g, 16g). After waiting for the water and the substance to get to room temperature, 20 degrees Celsius, Juan adds the different amounts of substance to the different beakers and takes the new temperature of each. What is the temperature of the initial reading? - 8 degrees Celsius - 12 degrees Celsius - 16 degrees Celsius - 18 degrees Celsius
- 14 degrees Celsius
Juan is conducting an experiment to see what occurs when a mystery substance is added to water. He measures out 250 ml of water in four beakers. Juan then measures out four different amounts of the mystery substance (4g, 8g, 12g, 16g). After waiting for the water and the substance to get to room temperature, 20 degrees Celsius, Juan adds the different amounts of substance to the different beakers and takes the new temperature of each. When Juan adds 16 grams of the mystery powder to the water, the temperature should become... 4 degrees Celsius - 4 degrees Celsius - 8 degrees Celsius - 14 degrees Celsius
Law of Conservation of Mass
This law states that, "Matter is not created or destroyed, it only changes form."
chemical symbol
One or two letters used to represent an element.
18
Oxygen atoms = ________
24
Oxygen atoms = ________
4
Oxygen atoms = ________
6
Oxygen atoms = ________
6
Silicon atoms = ________
2
Silver atoms = ________
reactants
Substances used during a chemical equation are indicated on the left side of the equation and are called ________.
2
What coefficient needs to be put in the blank to make this chemical equation balanced? Hint: T-chart
3, 3
What coefficients needs to be put in each blank to make this chemical equation balanced? Hint: T-chart
6, 6, 6
What coefficients needs to be put in each blank to make this chemical equation balanced? Hint: T-chart
yields
What does the arrow in the equation mean?
molecules
A coefficient in front of a chemical formula tells me the number of ________.
subscript
A small number to the right of a symbol that is written below the normal line of letters.
1, 2, 3, and 4
A student mixes two clear solutions. Which of the following is evidence that a chemical reaction is happening? 1. color change 2. odor change 3. temperature change 4. formation of a precipitate
the bubbles indicated a chemical change was occurring
A student placed 2 grams of baking soda in a balloon and 100 mL of vinegar in a flask. After stretching the opening of the balloon across the neck of the flask, the student raised it to dump the baking soda into the flask. He immediately observed foaming bubbles in the flask and the balloon began to expand. The student concluded that... - a physical change only was occuring - the bubbles indicated a chemical change was occuring - the baking soda and vinegar were products of a chemical reaction - the gas was oxygen
atoms
A subscripts to the right of a chemical symbol tells me the number of ________.
3
Aluminum atoms = ________
1
Barium atoms = ________
24
Carbon atoms = ________
4
Carbon atoms = ________
15
How many TOTAL atoms are in this chemical formula?
30
How many TOTAL atoms are in this chemical formula?
80
How many TOTAL atoms are in this chemical formula?
10
How many atoms TOTAL are there in this chemical formula?
4
How many chemical formulas are in this chemical equation?
5
How many chemical formulas are in this chemical equation?
1
How many coefficients are in this chemical equation?
32
Hydrogen atoms = ________
6
Hydrogen atoms = ________
chemical equation
I am a combination of chemical formulas used to describe what happens in a chemical reaction. What am I?
chemical formula
I am a combination of symbols and numbers that represent the number and types of elements (atoms) present in a compound. What am I?
coefficient
I am a number written in front of a chemical formula to show how many molecules of that substance are present.
precipitate
I am a solid that forms as a result of a chemical reaction. I will fall to the bottom of the container. What am I?
compound
I am a substance of two or more elements chemically combined and in a definite proportion. What am I?
chemical change
I am a type of change in which a substance (or substances) is changed into one or more new substances with different properties than the original substances. What am I?
physical change
I am a type of change in which the characteristics of a substance are only changed physically and the original properties stay the same. What am I?
3
Lithium atoms = ________
products
New substances formed during a chemical reaction are indicated on the right side of the equation and are called ________.
2
Nitrogen atoms = ________
chemical equation
The ________ ________ identifies the reactants and resulting products.
products
The ________ are formulas written on the right side of the arrow.
reactants
The ________ are the formulas written on the left side of the arrow symbol.
subscript
The ________ shows how many atoms of an element are present in a substance.
yields
The arrow in a chemical equation means ________.
CH4
The following is a model of a molecule of Methane. What is the chemical formula for Methane?
reactants
The starting substances in a chemical reaction are called the ________.
chemical reaction
When substances interact to form one or more new substances with different properties than the original substances.
one
When there is no subscript there is only ________ atom present.
J
Which of the following equations follows the Law of Conservation of Mass?
The model does not show why the atoms are bonding.
Which of the following is a limitation of the model above? - The model does not show what the products of the reaction are. - The model does not show what the reactants of the reaction are. - The model does not show why the atoms are bonding. - The model does not show the number of atoms involved in the reaction.
1, 1, 2, 1
Which of the following sets of coefficients would balance the following equation? - 1, 1, 2, 1 - 1, 2, 1, 2 - 2, 1, 1, 2 - 2, 1, 2, 1
D
Which of these equations shows rust, Fe2O3, forming when oxygen, O2, reacts with iron, Fe?
