chem test lab portion august 28

lets assume that the chemical identity of calcium chloride is not changed when it is mixed with water. suggest an experiment that could be done to test this hypothesis

an experiment could be when you mix calcium chloride and the water, you could let it sit to evaporate the water, and if what remains in the bag has the same properties as calcium chloride, it proves that the water does not change the chemical identity for the calcium chloride

based on the results of your controlled experiments, what combination of substances seems to be responsible for the observed temperature change in the overall reaction.

calcium chloride and phenol red

what is the outcome from mixing all the properties in the experiment?

it becomes warm, a gas is let go, gas bubbles, and turns into a yellow color

temperature changes are sometimes used as evidence to indicate that a chemical reaction has occurred. discuss whether a temperature change always indicates that a chemical reaction has occurred

it doesn't always mean a chemical reaction has occurred because there is a transfer of heat in many other process and it doesn't necessarily mean there has been a chemical reaction

what does calcium chloride look like?

its white circular shaped balls

was there a temperature change observed in any of the individual controlled experiments that was NOT observed in the overall reaction in part A? Explain.

no, because all of the controlled experiments had a temperature change

are temperature or color changes always observed at the same time as the formation of gas bubbles? explain

no, because the temperature changed and there were no bubbles forming at the same time

what color change was observed in the overall reaction? do the controlled experiments provide any evidence concerning the combination of chemicals responsible for the observed color change?

overall it was yellow. no, when we mixed calcium chloride and phenol red it turned into a magenta color so then we tried every other possible combination and still had the same color result

what does phenol red look like?

red liquid

what evidence suggest that a new chemical substance is produced in the overall reaction of the substances mixed in part A? what combinations of chemicals may be responsible for the new substances?

the evidence is produced in the overall reaction of the substances mixed in part A was when is started to foam up and the zip lock bag started to expand, the combinations responsible were sodium bicarbonate and water because when they are mixed together it produces carbon dioxide and bubbles

what controlled experiment(s) did you perform to evaluate if a liquid is necessary for the observed effects in part A? does any reaction occur in the absence of water?

we mixed all the powders and there was no effect. No, there is not reaction with the absence of water because every liquid is mixed with water so water is always included

what does sodium bicarbonate look like?

white powder