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Hot or Not?

based on 31 ratings
Author: Erin S.

2011 VIRTUAL SCIENCE FAIR ENTRY

Abstract

Most people who manually wash their dishes assume that hot water will kill the most microorganisms. The results from this experiment will help people know if hot water really does kill the most microorganisms. If swabs are grown from spoons washed in 10, 25, and 45 degrees Celsius, the least amount of microorganisms will grow from the spoons washed in 10 degrees Celsius. In order to do this the spoons were first soaked with milk to add microorganisms, because the new plastic spoons were sterile, and then swabbed after washed in the three different temperatures. The number of colonies grown after 48, 72, and 96 hours were counted and recorded. This process was repeated three times. After 96 hours the average colonies of the spoons washed in 10 degrees Celsius water was 4 colonies, the average colonies after washed in 30 degrees Celsius was 14 colonies, and the average colonies after washed in 45 degrees Celsius was 11 colonies. The results showed that the least colonies grew from the spoons washed in 10 degrees Celsius followed by the spoons washed in 45 degrees Celsius and lastly 30 degrees Celsius. 

Type

This project is in the Life Science category.

Grade

This project is appropriate for 5th and 6th graders.

Difficulty

This projects difficulty level was medium.

Cost

The cost of this project was approximately $20.

Safety Issues

In this experiment I had to make sure the water wasn’t too hot so it would not burn me. A safety issue in this project was growing microorganisms. To minimize this risk I did not come in contact with the microorganisms.

Time Taken to Complete Project

It took me approximately for me four days to finish this science experiment. I counted the colonies 48, 72, and 96 hours.

Objective

This project is about different temperatures of water on the cleanliness of dishes. The goal in this project is to find out what temperature of water kills microorganisms best. Also, if cold water kills just as much or more microorganisms, then if we used cold water we could improve the environment and our heating bills wouldn’t be as high.

Material and Equipment

The materials used in this project was 15 Petri dishes, one 125 milliliter bottle nutrient agar, 15 sterile swabs, a microwave, bleach, masking tape, a sharpie, 15 quart size Zip- Lock bags, a refrigerator, distilled water, stopwatch, ruler, 9 spoons, dawn soap, a sink, a drying rack, and a thermometer. I purchased these items at an online science store and a grocery store. Overall, these items were easy to find and purchase.

Introduction

People wash their dishes every day. Most people use hot water. Does hot water kill the most microorganisms? Also, if cold water kills just as much or more microorganisms, then if we used cold water we could improve the environment and our heating bills wouldn’t be as high.

In other experiments like mine, cold water was proven to kill the most microorganisms. In order to know if the types of microorganisms grown are harmful, they would have to be cultured. Due to limit of resources I was unable to culture the microorganisms grown.

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