1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
lozanna [386]
2 years ago
5

The reaction 4al (s) 3o2 (

Chemistry
2 answers:
irina [24]2 years ago
8 0
The reaction 4al (s) 3o2 (
g. → 2al2o3 (s) δh° = -3351 kj is exothermic________, and therefore heat is _____release ___ by the reaction.
Hunter-Best [27]2 years ago
6 0

<u>Answer:</u> The reaction is exothermic and therefore the heat is released by the reaction.

<u>Explanation:</u>

There are 2 types of reaction based on the heat of the reaction:

  • Exothermic reactions are defined as the reactions in which energy is released in the form of heat. The enthalpy change (\Delta H^o) of the reaction comes out to be negative for this kind of reaction.
  • Endothermic reactions are defined as the reactions in which energy is absorbed in the form of heat. The enthalpy change (\Delta H^o) of the reaction comes out to be positive for this kind of reaction.

For the given chemical reaction:

4Al(s)+3O_2(g)\rightarrow 2Al_2O_3(s);\Delta H^o=-3351kJ

As, the enthalpy change of the reaction is negative. The reaction is considered as an exothermic reaction.

Hence, the reaction is exothermic and therefore the heat is released by the reaction.

You might be interested in
An empty steel container is filled with 2.0 atm of H₂ and 1.0 atm of F₂. The system is allowed to reach equilibrium according to
Darina [25.2K]
H₂ (g) + F₂ (g) ⇌ 2 HF (g)

5 0
3 years ago
Any help would be appreciated. Confused.
masya89 [10]

Answer:

q(problem 1) = 25,050 joules;  q(problem 2) = 4.52 x 10⁶ joules

Explanation:

To understand these type problems one needs to go through a simple set of calculations relating to the 'HEATING CURVE OF WATER'. That is, consider the following problem ...

=> Calculate the total amount of heat needed to convert 10g ice at -10°C to steam at 110°C. Given are the following constants:

Heat of fusion (ΔHₓ) = 80 cal/gram

Heat of vaporization (ΔHv) = 540 cal/gram

specific heat of ice [c(i)] = 0.50 cal/gram·°C

specific heat of water [c(w)] = 1.00 cal/gram·°C

specific heat of steam [c(s)] = 0.48 cal/gram·°C

Now, the problem calculates the heat flow in each of five (5) phase transition regions based on the heating curve of water (see attached graph below this post) ...   Note two types of regions (1) regions of increasing slopes use q = mcΔT and (2) regions of zero slopes use q = m·ΔH.

q(warming ice) =  m·c(i)·ΔT = (10g)(0.50 cal/g°C)(10°C) = 50 cal

q(melting) = m·ΔHₓ = (10g)(80cal/g) 800 cal

q(warming water) = m·c(w)·ΔT = (10g)(1.00 cal/g°C)(100°C) = 1000 cal

q(evaporation of water) =  m·ΔHv = (10g)(540cal/g) = 5400 cal

q(heating steam) = m·c(s)·ΔT = (10g)(0.48 cal/g°C)(10°C) = 48 cal

Q(total) = ∑q = (50 + 800 + 1000 + 5400 + 48) = 7298 cals. => to convert to joules, multiply by 4.184 j/cal => q = 7298 cals x 4.184 j/cal = 30,534 joules = 30.5 Kj.

Now, for the problems in your post ... they represent fragments of the above problem. All you need to do is decide if the problem contains a temperature change (use q = m·c·ΔT) or does NOT contain a temperature change (use q = m·ΔH).    

Problem 1: Given Heat of Fusion of Water = 334 j/g, determine heat needed to melt 75g ice.

Since this is a phase transition (melting), NO temperature change occurs; use q = m·ΔHₓ = (75g)(334 j/g) = 25,050 joules.

Problem 2: Given Heat of Vaporization = 2260 j/g; determine the amount of heat needed to boil to vapor 2 Liters water ( = 2000 grams water ).

Since this is a phase transition (boiling = evaporation), NO temperature change occurs; use q = m·ΔHf = (2000g)(2260 j/g) = 4,520,000 joules = 4.52 x 10⁶ joules.

Problems containing a temperature change:

NOTE: A specific temperature change will be evident in the context of problems containing temperature change => use q = m·c·ΔT. Such is associated with the increasing slope regions of the heating curve.  Good luck on your efforts. Doc :-)

5 0
3 years ago
1. The most useful ore of aluminum is bauxite, in which Al is present as hydrated oxides, Al2O3⋅xH2O The number of kilowatt-hour
lianna [129]

*Answer:

Option A: 59.6

Explanation:

Step 1: Data given

Mass of aluminium = 4.00 kg

The applied emf = 5.00 V

watts = volts * amperes

Step 2: Calculate amperes

equivalent mass of aluminum = 27 / 3 = 9  

mass of deposit = (equivalent mass x amperes x seconds) / 96500

4000 grams = (9* amperes * seconds) / 96500

amperes * seconds = 42888888.9

1 hour = 3600 seconds

amperes * hours = 42888888.9 / 3600 = 11913.6

amperes = 11913.6 / hours

Step 3: Calculate kilowatts

watts = 5 * 11913.6 / hours

watts = 59568 (per hour)

kilowatts = 59.6 (per hour)

The number of kilowatt-hours of electricity required to produce 4.00kg of aluminum from electrolysis of compounds from bauxite is 59.6 kWh when the applied emf is 5.00V

5 0
2 years ago
How would you prepare a 1.00L solution of 2.00 M sodium hydroxide<br> (NaOH)*
Ede4ka [16]

Answer:

Explanation:

Molar mass of sodium hydroxide is = 100

any compund with its molar mass dissovled in 1L itres solution gives rise to 1M solution

40 g ------> 1L ---->1M

Xg  ------>1L------>2M

X g= 40*1*2/1*1 =80 gram

3 0
3 years ago
What is the pH of a solution which is 0.600 M in dimethylamine ((CH3)2NH) and 0.400 M in dimethylamine hydrochloride ((CH3)2NH2C
Viefleur [7K]

Answer:

pH = 11.05

Explanation:

It is possible to answer this question using Henderson-Hasselbalch formula:

pH = pka + log₁₀ [A] / [HA⁺]

Where A in this case is weak base (dimethylamine) and conjugate acid (HA⁺) is dimethylamine hydrochloride.

As Ka= Kw / Kb = 1x10⁻¹⁴ / 7.4x10⁻⁴ = 1.35x10⁻¹¹ And pKa is -log Ka = <em>10.87 </em> pH of the solution is:

pH = 10.87 + log₁₀ [0.600] / [0.400]

<em>pH = 11.05</em>

<em></em>

I hope it helps!

3 0
3 years ago
Other questions:
  • Which of the following is an example of the conversion of electrical energy to electromagnetic energy?
    9·2 answers
  • Which type of metal atoms affect the flame color ?
    8·1 answer
  • 0.556 g of a solid white acid are dissolved in water and completely neutralized by the addition of 52.38 mL of 0.396 M NaOH. Cal
    7·1 answer
  • Next
    6·1 answer
  • What volume unit is greater than one liter
    7·1 answer
  • Using the diameter information from the table, which answer lists the planets in the correct order, from largest to smallest?
    14·1 answer
  • Scientists have speculated that element 126 might have a moderate stability allowing it to be synthesized and characterized. Pre
    12·1 answer
  • Consider the following chemical reaction:
    5·1 answer
  • The structure and bonding of gold?
    8·2 answers
  • How many grams of nicotine (C10H14N2) are in a 0.125 mol sample of nicotine?
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!