Elements, Counting Atoms and Balancing Equations

How many Magnesium are in 10MgCl₂?

• 10

• 5

• 20

• 1

Tags

NGSS.MS-PS1-1

Number of N in (NH₄)₂CrO₄

• 1
• 2
• 8
• 16

Tags

NGSS.MS-PS1-1

What is a coefficient?

• The small number on the right of the chemical symbol.
• The large number to the left of a formula.

Tags

NGSS.MS-PS1-5

How many atoms of Carbon are in the compound C₂H₈O ?

• 8
• 2
• 1
• 11

Tags

NGSS.MS-PS1-1

Why do equations for chemical reactions need to be balanced?

• the law of balancing equations states that if equations are not balanced they will cause a dangerous explosion.

• matter is sometimes destroyed in chemical reactions, so you need to count atoms to see how much was lost.

• matter is conserved (not created or destroyed) , so you must have the same amount of atoms of an element in the reactants and products.

• matter is sometimes created in chemical reactions, so you need to count atoms to see how much was added.

Tags

NGSS.MS-PS1-5

Why is the following chemical equation not balanced?

H_{2 +} O₂ --> H₂O

• each side of the equation has a different number of oxygen atoms

• each side of the equation has a different number of hydrogen atoms

• each side has the same mass

• each side has different types of molecules

Tags

NGSS.MS-PS1-5

Is this balanced?...
Al + O₂ --> 2Al₂O₃

• Yes!
• NO!

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

2H₂ + O₂ ----> 2H₂O What is the product?

• ------>
• 2H₂O
• 2H₂+ O₂

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5

NGSS.MS-PS1-2

2H₂ + O₂ --------> 2H₂O What  are the reactants?

• ----->
• 2H₂O
• 2H₂ +O₂

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5

How many atoms are there TOTAL in:
H₂SO₄

• 6
• 5
• 7
• 3

Tags

NGSS.MS-PS1-1