Egg & Vinegar Lab

 The lab was based on an experiment performed in class where an egg was places in a jar filled with vinegar and what the results would turn out with the egg itself. This lab was in relation to habits of mind in choosing the right tool by using data and gathering information through an experiment in chemistry class.

Introduction

                What is the result or results of an egg being placed in a jar filled vinegar with a closed lid and left there for a few weeks? When an egg is placed in a jar filled with vinegar, the shell from the egg will crack and come off. The reason is due to the vinegar being a strong substance, chemical. Vinegar is a sour liquid that is obtained by a chemical decomposition of an organic substance such as the formation of alcohol from sugar or the souring of milk, by enzymatic action in the absence of oxygen. The power of hydrogen (pH) is a measure of the acidity of a solution in terms of activity of hydrogen. The acetic acid is vinegar and acids have a power of hydrogen that is less than 7.0. Vinegar has, among other things, a chemical called Acetic Acid (about 3% of it is acetic acid). Acids are sour tasting, such as the citric acid in lemons, the lactic acid in yogurt, or the malic acid in apples give those foods their sour taste. Egg shells contain calcium carbonate. Calcium carbonate in the egg shell reacts with vinegar. This is to form carbon dioxide which in the vinegar can be seen as bubbles. The component of the egg shell is CaCO3 and the component of vinegar is CH3CO2H. The volume of vinegar decreases partly because of the evaporation of acetic acid. However the main reason is due to the formula: CaCO3+2CH3CO2H= Ca(CH3CO2)2+CO2+H2O. The prediction the group members made was that pouring 75 mL of vinegar was the right amount to make at least some or most of the egg shell dissolve. It seemed as if pouring too much vinegar would make the entire egg itself dissolve. This was assumed because too much of something is usually not good, so with too much vinegar in the jar could have caused the egg to completely break off and ruin the purpose of the experiment. Also it was predicted that the size of the egg would increase due to the process of osmosis taking in the jar with the egg and the vinegar contained inside. In the lab, the purpose is to see the amount of vinegar that is used to make the shell dissolve from the egg and figure out what the mass of the shell is.

 

 

 

 

 

Materials

-         Vinegar

-         Egg

-         Glass Jar

-         Jar Lid

-         Beaker

 

 

 Procedure

 

                To begin this lab, all materials must be gathered. With a piece of paper and marker, write the names of the group members and label the jar. The group had to figure out how much vinegar is going to be added into the jar with the egg. Once a decision has been made, pour that amount of vinegar into the beaker and measure it to have accurate measurements. Place the egg into the jar before adding the vinegar. After the egg is in, pour all the vinegar from the beaker into the jar with the egg. Close the lid on the jar and leave it in an area where it is room temperature. Check results on the egg every week. The component of the egg shell is CaCO3. The component of vinegar is acetic acid (CH3CO2H). The volume of vinegar decreases partly because of the evaporation of acetic acid. But the main reason is due to the formula: CaCO3 + 2 CH3CO2H= Ca (CH3CO2)2 + CO2 +H2O. 

 

Calculations:

CaCO3 + 2 CH3CO2H – Ca (CH3CO2)2 + H2O + CO2

CaCO3 ~ Ca (CH3CO2)2 mL 

100 X 158         

Change of molar mass: 158 – 100 = 58 g/mol

Mass change of the egg: 6.64g  

100/x   =    58/ 6.64

 

X= 11.45g (CaCO3)

Moles of CaCO3 = 11.45g / 100(g/mol) = 0.1145 mole

Moles of CH3CO2H = 2 × 0.1145mole = 0.229 mole

The concentration of CH3CO2H = 0.229 mole ÷ (75-49) ml = 0.0088 mole/ml = 8.8 mole/L

PH = 5.5. The concentration of H+ in the solution is (H+) = 10-5.5 = 3.16×10-6

 

 

 

Analysis/ Conclusion

 

                The overall purpose of the lab was to figure whether or not the amount of vinegar poured into the jar that was predicted by the group themselves was accurate enough or not. In the experiment, the amount of vinegar poured in was 75 mL. What resulted in that was the egg shell did not break off entirely. However, the egg itself was completely softened. The component of the egg shell is CaCO3. The component of vinegar is acetic acid (CH3CO2H). Using the gathered information and making the calculations, and observing the egg and the vinegar in the jar time after time, there was a physical change shown in the egg and the vinegar. The vinegar began to decrease as well as the weight and the mass of the egg shell. In this case, more than 75 mL should have been added into the jar because only parts of the egg shell came off. A main point for this lab was the amount of vinegar first poured into the jar with the egg matters greatly. This is because the amount of vinegar will determine how much of the egg shell with come off.

 

 

 

 

 

Chemical Change Lab

This is a lab from chemistry class. The lab was from an experiment performed in class about recording and observing solutions that were mixed into an unknown solution. The chemical change lab was a relation to habits of mind in choosing the right tool by using information and data gathered for the experiment involving various chemicals and combining them.

Introduction

In this lab eight different solutions were mixed to find an unknown solution. The unknown solution was found by studying each mixture to determine if a new substance was formed. A chemical reaction is when one or more substances change to produce on or more new substances whose physical and chemical properties are different from the original substance. In chemical reactions the original substances are known as the reactants, and the substances created are known as products. The only way to prove that a chemical reaction has occurred is by the formation of a new substance, being that some chemical change is indirect. Evidence of chemical reactions includes the formation of a gas, formation of a precipitate, change in color, and change in odor. A chemical analysis is the only way to prove that a new substance has formed. An example is how a chemical change is happening as firewood is burning. The two products that are formed are carbon dioxide and water. Properties of a new substance include density, melting point, or boiling point, and must be different form the original substance.

A chemical equation is a representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products. A chemical equation tells the amount of each substance in the reaction. When balancing a chemical equation we follow the law of conservation of mass which states mass cannot be created or destroyed. This is because the products and reactants are made up of the same number and kind of atoms. In balancing the an equation there must be the same amount of atoms for each element on the reactants side as there is on the products side.

 

 

Procedure

Materials

Chemplate

Spatula

Solutions 1-8( Hydrochloric Acid, Sodium Carbonate, Sodium Hydroxide, Potassium Chromate, Calcium Chloride, Sodium Hydroxide Sulfide, Copper Sulfate, and a unknown solution)

Safety Materials

Before starting this lab put on all safety equipment such as goggles, gloves and an apron, pull back all loose clothing and hair. On lab paper write down all chemicals being used (listed above), and write a short description of each. Next mix every possible combination in the chemplate using 3-4 drops of each solution. Mix each mixture with a clean spatula. On the opposite side of lab paper record the result from observing each solution once mixed. Report the results by comparing the mixture with the original description of the solutions before they were mixed. Be sure to clean chemplate and spatula between each use.

 

 

Solutions

Observations

HCl+Na2(CO3)

Gas produced/ hissing sound

HCl+K2(CrO3)

Bubbles

Ca2(cl2)

color change

HCl+N4(HSO)

no reaction

HCl+Cu(SO4)

no reaction

Na2(Co3)+Na2(CO3)

no reaction

Na2(Co3)+K2(CO3)

no reaction

Na2(CO3+Ca2(Cl2)

color change

Na2(CO3)+N4(HSO)

no reaction

Na(OH)+K2(CrO3)

color change

Na(OH)+Cu(SO4)

no reaction

K2(CrO3)+Ca2(Cl2)

bubbling/ color change

K2(CrO3)+N4(HSO)

no reaction

K2(Cro3)+Cu(So4)

color change

Unknown+Na2(CO3)

no reaction

Unknown+Na2(CO3)

color change

Unknown+ Na(HO)

color change

Unknown+K2(CrO3)

no reaction

Unknown+Ca2(Cl2)

no reaction

Unknown+N4(HSO)

no reaction

Unknown+Cu(So4)

no reaction

The data in this table shows all the reaction which occurred while solutions 1-8 was mixed

together.

Conclusion

In this lab it was found that the unknown solution was solution number 5 which is calcium chloride. This conclusion was made after closely observing each mixture. Some mixtures had the formation of gas, change in color, change in odor, and formation of a precipitate. When we mixed solution 5 with other solutions there was no chemical change which makes this the unknown solution.

There can be many sources of error in this lab if the procedure is not properly followed. The main source of error is not waiting 30 seconds and observing after each solution has been mixed. Not cleaning the chemplate and spatula can also affect the outcome of this lab. Between each mixture use it is very important to clean the chemplate and spatula to stop error in the chemical reaction. There are many ways to improve this lab. One way is by washing all lab materials to make sure that the outcome is not a mixed result. For an even better outcome it is highly suggested that each mixture be observed for 30 seconds to make sure that there is a chemical reaction is taking place. Since the only way to prove if a chemical reaction has taken place is by the formation of a new substance it is important to study each solution to be positive that there is chemical change. Smelling, closely looking at the solution checking for gas, color change and precipitate are good ways to tell if a new substance has been formed.

What I learned from this lab was how to tell when a chemical reaction is taking place by using the evidence of a chemical reaction chart learned in class. This lab taught me that the only way to tell if a chemical reaction has taken place is by the formation of a new substance. Even though my group used the evidence of a chemical reaction it was hard to tell if there was chemical change because sometimes change came slow or it was not clear.