What is a chemical equation

What is a chemical equation

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In short...

It is a written representation of a chemical reaction.

A chemical reaction

Is always written in the form you see to the right. You always have something to the left an arrow and something to the right.

Multiple Choice

Which of the following is a chemical equation (Chem 7.02 Lv1)

• Na

• Na+ Cl-

• Na + Cl ------> NaCl

• NaCl

Equation writing

Writing equations follows a few rules and ideas

Reactants

The term reactants refer to the chemical compounds and elements to the left of the arrow. These are the compounds at the beginning of the chemical reaction.

The arrow

The arrow is there to show us the direction of the chemical reaction so that we know what the reactants are and the product will be. It is usually written pointing left to right.

Products

The term products refer to the chemical compounds and elements to the right of the arrow. These are the compounds left over after a chemical reaction.

Multiple Choice

Product (Chem 7.02 Lv1)

• the resulting chemical compounds after a chemical reaction has taken place.

• the chemical compounds going into a chemical reaction.

• describes a certain event of the natural world, but it does not attempt to explain how or why the event occurs.

• a reaction in which one element is substituted for another element in a compound.

Multiple Choice

Reactant (Chem 7.02 Lv1)

• the resulting chemical compounds after a chemical reaction has taken place.

• the chemical compounds going into a chemical reaction.

• describes a certain event of the natural world, but it does not attempt to explain how or why the event occurs.

• a reaction in which one element is substituted for another element in a compound.

Multiple Choice

What side of the arrow in a chemical equation is the product located? (Chem 7.02 Lv2)

• Right

• Left

• Above arrow

• It is not part of a chemical equation

Multiple Choice

What side of the arrow in a chemical equation is the reactant located? (Chem 7.02 Lv2)

• Right

• Left

• Above arrow

• It is not part of a chemical equation

Multiple Choice

Click on the picture

• That the reactions go both directions

• That you need to pour everything into separate beakers to make the reaction work

• The direction of the chemical reaction so you know what are the reactants and what are the products

• That there is heat applied to the chemical reaction.

Coefficient

These are numbers in front of chemical formulas to tell us the number of molecules involved in the chemical reaction or that we get out of a chemical reaction.

Just like with subscripts we do not write 1's

State of Matter

• Some times in equations you have state of matter symbols following the formula

• (s) = solid meaning the compound is in the solid-state when reacted or after the reaction

• (aq) = aqueous meaning a chemical is dissolved in water when reacted or after the reaction

State of Matter

• Some times in equations you have state of matter symbols following the formula

• (g) = gas meaning the compound was in a gas state when reacted or after the reaction

• (l) = liquid meaning the compound was in a liquid state when reacted or after the reaction

Multiple Choice

What does the subscript number in a chemical formula represent? (Chem 7.02 Lv3)

• Number of molecules

• Number of times the reaction need to happen

• Number of atoms in a compound

• Number of pounds of chemicals needed for the reaction

Multiple Choice

What does the coefficient in front of the chemical compounds represent? (Chem 7.02 Lv3)

• Number of molecules

• Number of times the reaction need to happen

• Number of products

• Number of pounds of chemicals needed for the reaction

Multiple Choice

What state of matter is H₂O in for the chemical equation below?

HC₂H₃O₂(aq) + NaHCO₃(s) -----> CO₂(g) + H₂O(l) + NaC₂H₃O₂(aq)

(Chem 7.02 Lv3)

• Solid

• Liquid

• Gas

• Aqueous

Multiple Choice

What does it mean when a chemical is aqueous? (Chem 7.02 Lv3)

• It has melted

• It does not dissolve in water

• It is dissolved in water

• It will only react in gas form

Multiple Choice

What state of matter is CO₂ in for the chemical equation below?

HC₂H₃O₂(aq) + NaHCO₃(s) -----> CO₂(g) + H₂O(l) + NaC₂H₃O₂(aq)

(Chem 7.02 Lv3)

• Solid

• Liquid

• Gas

• Aqueous

Multiple Choice

What state of matter is NaHCO₃ in for the chemical equation below?

HC₂H₃O₂(aq) + NaHCO₃(s) -----> CO₂(g) + H₂O(l) + NaC₂H₃O₂(aq)

(Chem 7.02 Lv3)

• Solid

• Liquid

• Gas

• Aqueous

Multiple Choice

What state of matter is HC₂H₃O₂ in for the chemical equation below?

HC₂H₃O₂(aq) + NaHCO₃(s) -----> CO₂(g) + H₂O(l) + NaC₂H₃O₂(aq)

(Chem 7.02 Lv3)

• Solid

• Liquid

• Gas

• Aqueous

Heat applied

The double arrow

If you see a reaction with a double arrow as seen to the right that means the reaction has reached equilibrium.

This means there are equal amounts of reactants and products.

This is because the product AB can be broken apart in the reaction and form A + B. So the reaction happens in both directions

Multiple Choice

Click on the picture

• That the reactions go both directions

• That you need to pour everything into separate beakers to make the reaction work

• That there are no products only reactants

• That there is heat applied to the chemical reaction.

To review