How many grams of ko2 are needed to form 6.5 g of o2?

The mass of needed is 19.3 grams.

Explanation:

To calculate the number of moles, we use the equation:

     .....(1)

Given mass of oxygen gas = 6.5 g

Molar mass of oxygen gas = 32 g/mol

Putting values in equation 1, we get:

The chemical equation follows:

By Stoichiometry of the reaction:

3 moles of oxygen gas is produced by 4 moles of

So, 0.203 moles of oxygen gas is produced by = of

Now, calculating the mass of by using equation 1, we get:

Molar mass of = 71.1 g/mol

Moles of = 0.271 moles

Putting values in equation 1, we get:

Hence, the mass of needed is 19.3 grams.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.