Dishwasher tablets contain chemicals which remove dirt from dishes - Scottish Highers Chemistry - Question 9 - 2017

Another action of the bleach produced by dishwasher tablets is to break down colored compounds, which helps to remove stains from dishes.

1. First, calculate the number of moles of hydrogen peroxide (H₂O₂):

   $\text{moles of H₂O₂} = \frac{0.051 \text{ g}}{34 \text{ g/mol}} = 0.0015 \text{ moles}$

2. According to the reaction: $2 \text{ H₂O₂} (l) \rightarrow 2 \text{ H₂O} (l) + \text{ O₂} (g)$ 1 mole of H₂O₂ produces 0.5 moles of O₂. Therefore:

   $\text{moles of O₂} = 0.0015 \text{ moles H₂O₂} \times \frac{0.5 \text{ moles O₂}}{1 \text{ mole H₂O₂}} = 0.00075 \text{ moles O₂}$

3. Now calculate the volume of O₂ produced:

   $\text{Volume of O₂} = 0.00075 \text{ moles} \times 24,000 \text{ cm³/mole} = 18 \text{ cm³}$

The small, water-soluble molecules made when proteins are completely broken down are called amino acids.

The functional group circled is the amine group (–NH₂).

One possible structural formula for an amino acid derived from this protein chain is:

   H   O
   |   ||
H₂N–C–C–OH
   |   
   R   

Where R could represent a variety of side chains found in amino acids.

The term used to describe the change in shape of enzyme molecules is denaturation.

A change in conditions that would cause the enzyme molecules to change shape is an increase in temperature or alteration in pH levels.

The type of reaction shown in the first stage of producing TAED is called a condensation reaction.

The structural formula for TAED (Tetraacetylethylenediamine) is:

      O   O
      ||  ||
  H₃C–C–N–C–C–H₃
      ||  ||
      O   O

Where each acetyl group is attached to the nitrogen atoms.