Chemical Reactions Fireworks are a result of chemical reactions.
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Transcript of Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a...
![Page 1: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/1.jpg)
Chemical Reactions
![Page 2: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/2.jpg)
Evidence for Chemical Reactions• There are four observations which indicate a
chemical reaction is taking place.
1. A gas is released.
• Gas may be observed in many ways in a reaction from light fizzing to heavy bubbling.
• Shown here is the release of hydrogen gas from the reaction of magnesium metal with acid.
![Page 3: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/3.jpg)
Evidence for Chemical Reactions2. An insoluble solid is produced.
• A substance dissolves in water to give an aqueous solution.
• If we add two aqueous solutions together, we may observe the production of a solid substance.
• The insoluble solid formed is called a precipitate.
![Page 4: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/4.jpg)
Evidence for Chemical Reactions3. A permanent color change is observed.
• Many chemical reactions involve a permanent color change.
• A change in color indicates that a new substance has been formed.
![Page 5: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/5.jpg)
Evidence for Chemical Reactions4. An energy change is observed.
• Examples of a heat energy change in a chemical reaction are heat and light given off.
![Page 6: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/6.jpg)
Writing Chemical Equations
• A chemical equation describes a chemical reaction using formulas and symbols. A general chemical equation is:
A + B → C + D
• In this equation, A and B are reactants and C and D are products.
![Page 7: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/7.jpg)
States of Matter in Equations• When writing chemical equations, we usually
specify the physical state of the reactants and products.
A(g) + B(l) → C(s) + D(aq)
• In this equation, reactant A is in the gaseous state and reactant B is in the liquid state.
• Also, product C is in the solid state and product D is in the aqueous state (water solution).
![Page 8: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/8.jpg)
Chemical Equation Symbols• Here are several symbols used in chemical
equations:
Symbol Interpretation of Chemical Equation Symbol
→ Produces, yields, gives
+ Reacts with, added to, plus
NR No reaction
(s) Solid substance or precipitate
(l) Liquid substance
(g) Gaseous substance
(aq) Aqueous solution
![Page 9: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/9.jpg)
Reactivity of Metals Lab Results
Magnsium metal
Copper metal
Zincmetal
→
→
→
Mg(NO3)2 Cu(NO3)2 Zn(NO3)2 AgNO3
↓ ↓ ↓ ↓
Magnesium Copper Zinc Silver nitrate nitrate nitrate nitrate
![Page 10: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/10.jpg)
A Chemical Reaction• Lets look at a chemical reaction that occurred in the
metal reactivity lab:
Cu(NO3)2(aq) + Zn(s) →Zn(NO3)2(aq) + Cu(s)
• The equation can be read as follows:
– Aqueous copper nitrate is added to solid zinc and yields aqueous zinc nitrate and solid copper.
– Notice zinc replaced copper in the nitrate solution and solid copper formed as a precipitate.
![Page 11: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/11.jpg)
A Chemical Reaction• Here’s another chemical reaction that occurred in the
metal reactivity lab:
2AgNO3(aq) + Mg(s) →Mg(NO3)2(aq) + 2Ag(s)
• The equation can be read as follows:
– Aqueous silver nitrate is added to solid magnesium and yields aqueous magnesium nitrate and solid silver.
– Notice magnesium replaced silver in the nitrate solution and solid silver formed as a precipitate.
![Page 12: Chemical Reactions. Evidence for Chemical Reactions There are four observations which indicate a chemical reaction is taking place. 1.A gas is released.](https://reader035.fdocuments.us/reader035/viewer/2022070403/56649f2e5503460f94c47ed6/html5/thumbnails/12.jpg)
Metal Activity Series• When a metal undergoes a replacement reaction,
it displaces another metal from a compound or aqueous solution.
• The metal that displaces the other metal does so because it is more active.
• The activity of a metal is a measure of its ability to compete in a replacement reaction.
• In an activity series, a sequence of metals is arranged according to their ability to undergo reaction.
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Activity Series• Metals that are most reactive appear first in the
activity series. These will replace any metals that are to the right of them.
• Metals that are least reactive appear last in the activity series.
• The relative activity series is:
Li > K > Ba > Sr > Ca > Na > Mg >Al > Mn > Zn > Fe > Cd > Co > Ni > Sn > Pb > Cu > Ag > Hg >Au