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
atroni [7]
3 years ago
8

What is the total amount of heat released when 94.0 g water at 80.0 °C cools to form ice at −30.0 °C?

Chemistry
1 answer:
Wewaii [24]3 years ago
6 0

Answer:

The total amount of heat released  is  68.7 kJ

Explanation:

Given that:

mass of water = 94.0 g

moles of water = 94 / 18.02 = 5.216

80⁰C   ------>  0⁰C  -------->    -30⁰C

Q1 = m Cp dT

      = 94 x 4.184 x (0 - 80)

     = -31463.68 J

     = -31.43 kJ

Q2 = 6.01 x 10^3 x 5.216

    = - 31348.16 J

   = -31.35 kJ

Q3 = - 94 x 2.09 x 30

    = - 5893.8 J

   = -5.894 kJ

Total heat = Q1 + Q2 + Q3  = -31.43 kJ  + (-31.35 kJ  ) + (-5.894 kJ )  = -68.7 kJ

Total heat released = -68.7 kJ

Note that the "negative sign" simply indicates heat released, therefore no need to put it in the answer.

You might be interested in
The acid-dissociation constant of hydrocyanic acid (hcn) at 25.0 °c is 4.9 ⋅ 10−10. what is the ph of an aqueous solution of 0.0
vodomira [7]
According to the reaction equation:

and by using ICE table:

              CN-  + H2O ↔ HCN  + OH- 

initial  0.08                        0          0

change -X                        +X          +X

Equ    (0.08-X)                    X            X

so from the equilibrium equation, we can get Ka expression

when Ka = [HCN] [OH-]/[CN-]

when Ka = Kw/Kb

               = (1 x 10^-14) / (4.9 x 10^-10)

               = 2 x 10^-5

So, by substitution:

2 x 10^-5 = X^2 / (0.08 - X)

X= 0.0013

∴ [OH] = X = 0.0013 

∴ POH = -㏒[OH]

            = -㏒0.0013

            = 2.886 

∴ PH = 14 - POH

         = 14 - 2.886 = 11.11
5 0
3 years ago
I want to know the steps.
Artyom0805 [142]

The answer for the following problem is described below.

<em><u> Therefore the standard enthalpy of combustion is -2800 kJ</u></em>

Explanation:

Given:

enthalpy of combustion of glucose(ΔH_{f} of C_{6}H_{12} O_{6}) =-1275.0

enthalpy of combustion of oxygen(ΔH_{f} of O_{2}) = zero

enthalpy of combustion of carbon dioxide(ΔH_{f} of CO_{2}) = -393.5

enthalpy of combustion of water(ΔH_{f} of H_{2} O) = -285.8

To solve :

standard enthalpy of combustion

We know;

ΔH_{f}  = ∈ΔH_{f} (products) - ∈ΔH_{f} (reactants)

C_{6}H_{12} O_{6} (s) +6 O_{2}(g) → 6 CO_{2} (g)+ 6 H_{2} O(l)

ΔH_{f} = [6 (-393.5) + 6(-285.8)] - [6 (0) + (-1275)]

ΔH_{f} = [6 (-393.5) + 6(-285.8)] - [0 - 1275]

ΔH_{f} = 6 (-393.5) + 6(-285.8)  - 0 + 1275

ΔH_{f} = -2361 - 1714 - 0 + 1275

ΔH_{f} =-2800 kJ

<em><u> Therefore the standard enthalpy of combustion is -2800 kJ</u></em>

7 0
3 years ago
Sean drew this diagram and labeled an unknown gas as gas A. Which gas does A represent?
ANEK [815]
Gas A is Carbon Dioxide
3 0
3 years ago
Read 2 more answers
Which is a diatomic molecule?<br> A. He <br> B. O2 <br> C. NaCl <br> D. CuF2
katrin2010 [14]

O2 is the right answer                      

4 0
4 years ago
Read 2 more answers
Susana heats up a sample of red crystals. While the sample is being heated, a gas is released and a blue powder is left after th
frutty [35]

Answer: Compound

Explanation:

Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper Cu

Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water H_2O

2H_2O\rightarrow 2H_2+O_2

Thus as it give that  the red sample on being heated, a gas is released and a blue powder is left after the heating. Thus the given sample is a compound.

5 0
3 years ago
Read 2 more answers
Other questions:
  • Draw a structure for a compound that meets the following description: An optically active compound, C5H10O with an IR absorption
    14·1 answer
  • Which response includes all of the following processes that are accompanied by an increase in entropy?
    15·1 answer
  • Why is energy required to break a chemical bond
    13·1 answer
  • A balloon contains a fixed amount of helium. If the initial conditions are 1.12 liters, 3.00 atmospheres, and 19 degrees Celsius
    7·1 answer
  • How many electron shells/orbitals will be around the nucleus of an atom of aluminum?
    11·2 answers
  • Does an electric iron may have a lower wattage than a LED lightbulb
    7·1 answer
  • 7. Which of the following is a proof that light travels in a straight line?
    8·1 answer
  • The atomic number of an element:
    6·1 answer
  • Which Group is in the leftmost column on the periodic table?
    15·2 answers
  • Magnesium reacts with acid to give a salt
    8·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!