5.3 Are all foods created equal?

Safety Reminders Wear safety goggles Do not eat foods from this lab—they are lab materials Point the test tube away from you and your partners Keep the candle in the pie pan Be careful of hot wax from the candle If glass breaks tell your teacher—don’t touch the broken glass

Preparing lab Designate one cup as your clean water cup and the other cup as your cup that you will use to cool the food down. Pour exactly 20 mL from the clean water cup into a graduated cylinder and then into your test tube. Put your test tube clamp securely around the test tube. Insert your thermometer into the test tube and allow it to rest for 30 seconds. Read the temperature at eye level and record it as the starting temperature for trial 1. Leave the thermometer in the test tube. Place your candle in the pie plate and your teacher will light it.

Finding energy in a marshmallow Tear about ¼ of the marshmallow off and place it on the dissecting needle. Rotate the needle with marshmallow over the flame unit the entire marshmallow is on fire. Immediately hold the burning marshmallow on the dissecting needle under the test tube so the tip of the flame is touching the test tube like figure 5.4 on page 106. DO THIS OVER THE PIE PLATE TO CATCH ANY MARSHMALLOW THAT MAY FALL. Keep the marshmallow under the test tube until the fire goes out. Wait 10 seconds. At eye level, read the temperature of the thermometer in the test tube and record the ending temperature in your data table. Subtract that starting temperature from the ending temperature to determine the total change in temperature and record this number in your data table. Dip the marshmallow in the cup designated to cool down food. Remove remains of marshmallow from the needle with a paper towel. Carefully dispose of the water in the test tube as directed by your teacher. Repeat steps 2-17 with a second piece of marshmallow.

Finding energy in a sunflower seed Push on the sides of your sunflower seed to remove the shell. Gently stick the very tip of the dissection needle into the fattest part of the sunflower seed, be careful not to split the seed. Rotate the needle with sunflower seed over the flame unit the entire seed is on fire. Immediately hold the burning seed on the dissecting needle under the test tube so the tip of the flame is touching the test tube DO THIS OVER THE PIE PLATE TO CATCH ANY SEED THAT MAY FALL. Keep the seed under the test tube until the fire goes out. Wait 10 seconds. At eye level, read the temperature of the thermometer in the test tube and record the ending temperature in your data table. Subtract that starting temperature from the ending temperature to determine the total change in temperature and record this number in your data table. Dip the sunflower seed in the cup designated to cool down food. Remove remains of the sunflower seed from the needle with a paper towel. Carefully dispose of the water in the test tube as directed by your teacher.

Data Calculate the average temperature change for the marshmallow and sunflower seed. Report averages to the class.