The correct answers are as follows:
1. Aluminium will not be useful as food wrapping if it has a much lower melting point.
Aluminum is a metallic element that is malleable and soft, thus, it is easy to beat it into thin sheet, which are used to package food. The thin sheet is called aluminium foil. Aluminum is useful as a food wrapping because it has high temperature and thus, it does not react with food (the hotness of the packaged food is not capable of melting the metal). If the melting point of aluminium is lower, this implies that little temperature, such as the one from hot food will be able to melt aluminum foil, thus allowing the food to be contaminated with the metal.
2. When bleach react with fabric dye chemical change occur in the fabric.
The major element in bleach is chlorine. When laundry bleach is added to a fabric, the chlorine component of the bleach will react with the fabric dye and cause a colour change in the fabric. This type of change is called chemical change, because the original colour of the fabric can not be recovered.
3. Every substance has specific properties, which can be used to identify it. Two of such specific properties are melting point and boiling point. Melting point refers to a specific temperature at which a solid substance will melt while boiling point refers to a specific temperature at which a liquid substance will boil and turn to steam.
Water for instance has a boiling point of 100 degree Celsius. To find out if an unknown substance is water, one can determine the boiling point of such liquid. A boiling point of 100 degree Celsius will strongly signify that the substance is probably water. The same thing applies to melting point. If the specific boiling and melting point of substances are known, then they can be used to identify them.
Answer:
It is equal to the number of moles of acid that reacted. When Oxalic acid is your limiting reactant it is the # of moles of oxalic acid used. When NaOH is your limiting reactant it is equal to the number of moles of NaOH used.
Answer:
II) Objects made of silver become tarnished.
Explanation:
Physical properties are the properties which can be observed without changing identity of substance.
Chemical properties are the properties which describe how the substance changes into the different substance completely.
Boiling is an example of physical change in state of the substance. Color is also an example of physical property like boiling point and hence these are constants. The reason of the color is that the chromium ions shows certain colors as the electrons are excited due to absorption of the light. The tarnishing of the silver is an example of the chemical change which occurs due to the reaction of the silver with oxygen. This is also known as corrosion.
The following are the steps to complete and balnce the equation for the given reaction
<u>Explanation:</u>
We are given, NO2– is oxidized to NO3– and Ag is reduced to Ag
NO2– + Ag+ -----> NO3– + Ag(s)
Step 1) Assign the oxidation state to each element reaction
NO2– + Ag+ -----> NO3– + Ag(s)
N= +3 N = +5
O = -2 O = -2
Ag = +1 Ag = 0
NO2– -----> NO3– ………oxidation half reaction
Ag+ -----> Ag(s) ……….reduction half reaction
Step 2) Balance the element other than O and H
NO2– -----> NO3–
Ag+ -----> Ag(s)
Step 3) Balance the O by adding 1 H2O for 1 O
NO2– + H2O -----> NO3–
Ag+ -----> Ag(s)
Step 4) Balance the H by adding H+
NO2– + H2O -----> NO3– + 2H+
Ag+ -----> Ag(s)
Step 5) Balance the charge by adding electron
NO2– + H2O -----> NO3– + 2H+ + 2e-
Ag+ + 1e------> Ag(s)
Step 6) Balance the electron in both half reaction
NO2– + H2O -----> NO3– + 2H+ + 2e-
2 Ag+ + 2e------> 2 Ag(s)
<span>Metals tend to lose electrons and form electro-positive ions / cations.</span>
