Question

look at the equations below. first, balance the equation using the masses given to you. then, identify the reactants and the products. finally, answer any other questions pertaining to each equation.

____55____ g 4na + 15g o₂ → 70g 2na₂o

what are the reactants? ____4na, o₂__ what is the product? __na₂o____
are there more reactants, more products, or are they the same?______
why?______

35g cl₂ + 15g 2ki → 25g kcl + ____25____ g i₂

what are the reactants? ____cl₂, 2ki__ what are the products? __i₂____
which product is an element? ____cl₂__ which product is a compound? ____
is the reaction above a physical or chemical change? ______
how do you know? ______

____45____g 2na + 30g 2hcl → 50g h₂ + 25g 2nacl

what are the reactants? ____2na, 2hcl__ what are the products? __h₂, 2nacl____
which product is an element? ____h₂__ which product is a compound? ____

Explanation:

Step1: Analyze the first reaction (Na and O₂)

Reactants are on the left of the arrow: \(4\text{Na}\) and \(\text{O}_2\). Product is on the right: \(2\text{Na}_2\text{O}\). Mass of reactants: \(55\,\text{g} + 15\,\text{g} = 70\,\text{g}\), mass of product is \(70\,\text{g}\). So they are the same (Law of Conservation of Mass).

Step2: Analyze the second reaction (Cl₂ and KI)

Reactants: \(\text{Cl}_2\) and \(2\text{KI}\). Products: \(\text{KCl}\) and \(\text{I}_2\). \(\text{I}_2\) is an element (only I atoms), \(\text{KCl}\) is a compound (K and Cl). It's a chemical change (new substances formed, like \(\text{KCl}\) and \(\text{I}_2\) from \(\text{Cl}_2\) and \(\text{KI}\)).

Step3: Analyze the third reaction (Na and HCl)

Reactants: \(2\text{Na}\) and \(2\text{HCl}\). Products: \(\text{H}_2\) and \(2\text{NaCl}\). Mass of reactants: \(45\,\text{g} + 30\,\text{g} = 75\,\text{g}\), mass of products: \(50\,\text{g} + 25\,\text{g} = 75\,\text{g}\) (conservation of mass).

Answer:

First Reaction:

• Reactants: \(4\text{Na}\), \(\text{O}_2\)
• Product: \(2\text{Na}_2\text{O}\)
• Reactants and products mass: Same (Law of Conservation of Mass, mass of reactants = mass of product: \(55 + 15 = 70\), product mass is \(70\))

Second Reaction:

• Reactants: \(\text{Cl}_2\), \(2\text{KI}\)
• Products: \(\text{KCl}\), \(\text{I}_2\)
• Element product: \(\text{I}_2\)
• Compound product: \(\text{KCl}\)
• Change: Chemical (new substances formed)

Third Reaction:

• Reactants: \(2\text{Na}\), \(2\text{HCl}\)
• Products: \(\text{H}_2\), \(2\text{NaCl}\)
• Element product: \(\text{H}_2\)
• Compound product: \(2\text{NaCl}\)