Explain why some alloys’ strength increases with aging then decreases again.

Pre-Laboratory Question: Investigating Chemical Reactions

Balance each of the following equations, and classify each of the reactions by type.

Laboratory Questions

Activity 1: Synthesis Reaction

Describe all of the signs that indicated a chemical reaction occurred.

Describe the temperature change that occurred during this reaction. Is heat required or produced during the reaction?

Describe any other changes that were observed in the steel wool. What reaction might create such a change?

Write a balanced equation for the reaction of the steel wool with oxygen. Be sure to include heat energy in the reaction.

Activity 2: Decomposition Reaction

What gases could be produced from decomposing hydrogen peroxide?

Which gas was produced?

Write a balanced equation for the decomposition of hydrogen peroxide.

Activity 3: Single-Replacement Reaction

What gases could be produced from hydrochloric acid (HCl)?

Which gas was produced?

Write a balanced equation for the reaction of magnesium with hydrochloric acid.

Why did you need to tilt the splint at a 45-degree angle?

a. Write a balanced equation for the reaction initiated by the burning splint.

b. Classify the reaction initiated by the burning splint.

Activity 4: Double-Replacement Reaction

Describe the reaction of sodium bicarbonate and vinegar.

Refer to the section in the Background titled, “Standard Tests Gaseous Products.” Use a flaming splint and a glowing splint to identify the gas above the liquid in the cup. Write the name and formula of the gas in the space provided.

Write a balanced chemical equation for this double-replacement reaction.

One of the two products of this reaction is carbonic acid (H₂CO₃), which immediately forms water and the gas you identified after exposure to the flaming and glowing splints. Write a balanced equation showing the decomposition of carbonic acid.

Activity 5: Combustion Reaction

Explain why water appears on the inside of the glass test tube.

Write a balanced equation for the combustion reaction.

Activity 6: Precipitation Reaction

Write a balanced equation for the precipitation reaction.

Which product in the above reaction is the precipitate?

Discussion Questions

Predict the product(s) of the following equations. Balance the equations, and classify each of the reactions by type.

Complete combustion of 4.80 g of a hydrocarbon produced 14.5 g of CO2 and 7.44 g of H2O. What is the empirical formula for the hydrocarbon?

Balance the redox reaction

FeSO₄ + H₂SO₄ + KMnO₄ ---> Fe₂(SO₄)₃ + K₂SO + MnSO₄ + H₂O

What is the coefficient of FeSO₄ in the balanced equation? Please show work.

explain your answer step by step, i already have the answer but i need the explnations and type your answer, thanks

4 FeS₂   +   11 O₂    ®    2 Fe₂O₃    +    8 SO₂

1.    How many moles of oxygen are required to react with 3.75 moles of FeS₂?

2.    How many moles of Fe₂O₃ are formed when 2.83 moles of oxygen reacts with

       excess FeS₂?

3.    How many moles of SO₂ are formed when 2.81 moles of Fe₂O₃ are formed?

4.    How many grams of SO₂are formed when 1.00 mol of FeS₂ reacts?

5.    How many moles of O₂ are required to from 75.8 grams of Fe₂O₃?

6.    How many grams of Fe₂O₃ are formed when 187 grams of FeS₂ react with excess   

       oxygen?

7.    How many grams of oxygen are required to form 67.8 grams of Fe₂O₃?

8.    How many grams of FeS₂ are required to react with excess oxygen to produce

       77.0 grams of SO₂?

9.    How many molecules of SO₂ are formed when 27.0 grams of FeS₂ react?

Percent Yield

10.   If 30.7 grams of Fe₂O₃ are obtained from the reaction of 85.3 grams of FeS₂ with

       excess oxygen, what is the percent yield?

11.   What is the percent yield if 130 grams of SO₂ are obtained from the reaction of        140 grams of FeS₂ with excess oxygen?

Limiting Reactant

12.   What is the maximum amount of Fe₂O₃ that can be prepared from 57.8 grams of

       FeS₂ and 92.5 grams of O₂? What is the limiting reactant?

13.   How many grams of SO₂ can be prepared from 86.2 grams of FeS₂ and

       125.3 grams of oxygen? How many grams of each reactant and product are     present at the end of the reaction?

14.   What is the percent yield if 118 grams of SO₂ are produced from the reaction of

       135 grams of FeS₂ and 200 grams of oxygen?

1/ the total volume of hydrogen gass needed to fill the Hindenburge was 2x10^8 liters at 1 atm and 25*C. How Much energy was evolved when it burned ?

H2(g) + .5O2(g) ----> H2O(I) ∆H* = -286Kj

2/ The heat of formation of iron(III) oxide is -826KJ/mol. Calculate the heat of the reaction when a 55.8 g sample of iron is reacted with an excess of oxygen gas.

4Fe(s) + 3O2(g) -----> 2Fe2O3(s)

3/ the vapor pressure of water at 25*Celcius is 23.8 torr. Determine the mass of glucose( molar mass= 180g/mol) needed to add to 500 grams of water to change the vapor pressure to 23.1 torr.

4/ Consider the reaction H2(g) + .5O2(g) ----> H2O(I) ∆H*= -286 Kj

which of the following is true?

A/ The reaction is exothermic

B/ The reaction is endothermic

C/ The enthalpy of the products is less than that of the reactants.

D/ Heat is absorbed by the system

E/ The reaction is exothermic and the enthalpy of the products is less than that of the reactants.

(a) Starting with the orbital diagram of a sulfur atom, describe the steps needed to construct hybrid orbitals appropriate to describe the bonding in SF2. (b) what is the name given to the hybrid orbitals. (c) sketch the large lobes of these hybrid orbitals. (d) Would the hybridization scheme in part (a) be appropriate for SF4? Explain

It is important to understand what an amino acid bond is, where at is located within a protein. Why is this such as table bond and what the products if it's hydrolysis?

A solution of 0.2152M NaOH is used to neutralize 15.00mL H2SO4 solution.

H2SO4(aq) + 2NaOH(aq) ? Na2SO4(aq) + 2H2O(l)

If 32.59mL NaOH solution is required to reach the endpoint, what is the molarity of the H2SO4 solution?

3. Molecular bromine is 24% dissociated at 1600K and 1.00 bar in the equilibrium:

Br​​2 (g)-------- 2Br(g)

Calculate:

a) the equilibrium constant K at 1600K (8)

b) the standard Gibbs energy of reaction 4)

C) K at 2000K , given that ∆r H = +112kj/mol over the temperature range. (6)

PLease explain in detail the function of Lithium Fluoride and aluminium in the Lit/Al layer in organic solar cells. Please describe the organic chemistry structure in regards to the role.

How much heat is evolved in converting 1.00 mol of steam at 155.0 ∘C to ice at -45.0 ∘C? The heat capacity of steam is 2.01 J/(g⋅∘C) and of ice is 2.09 J/(g⋅∘C). Express your answer in units of kilojoules Assume the system is at atmospheric pressure.

Thanks all!!

The mass of a 270. mL beaker is 178 g when empty. Determine its mass when filled with the following substances.

(a) water (density 0.9970 g/cm³ at 20°C)

____ g
(b) alcohol (density 0.7893 g/cm³ at 20°C)
____ g
(c) mercury (density 13.546 g/cm³ at 20°C)
____ g
(d) Explain why mercury containing pollutants are usually found in the mud at the bottom of a lake of stream.

-Mercury has a negative charge and is attracted to the positively charged particles on the lake or stream bed.

-Mercury containing pollutants do not float.    

-Mercury is denser, and therefore sinks to the bottom of the lake or stream.

Part A

It takes 47.0 J to raise the temperature of an 9.50 g piece of unknown metal from 13.0∘C to 24.8 ∘C. What is the specific heat for the metal?

Express your answer with the appropriate units. Cs=

Parts B and C

The next two questions pertain to silver. They have nothing to do with unknown metal described in Part A.

Part B

The molar heat capacity of silver is 25.35 J/mol⋅∘C. How much energy would it take to raise the temperature of 9.50 g of silver by 19.5 ∘C?

Express your answer with the appropriate units. q=

Part C

What is the specific heat of silver?

Express your answer with the appropriate units.