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3 years ago

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.

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Exposing a 250 mL sample of water at 20.∘C to an atmosphere containing a gaseous solute at 27.59 kPa resulted in the dissolution

ElenaW [278]

Answer : The solubility of this gaseous solute will be, $5.18\times 10^{-5}g/mL$

Explanation :

First we have to calculate the concentration of solute.

$\text{Concentration of solute}=\frac{Mass}{Volume}=\frac{4.51\times 10^{-3}g}{250mL}=1.80\times 10^{-5}g/mL$

Now we have to calculate the Henry's law constant.

Using Henry's law :

$C=k_H\times p$

where,

C = concentration of solute = $1.80\times 10^{-5}g/mL$

p = partial pressure = 27.59 kPa

$k_H$ = Henry's law constant = ?

Now put all the given values in the above formula, we get:

$1.80\times 10^{-5}g/mL=k_H\times (27.59kPa)$

$K_H=6.52\times 10^{-7}g/mL.kPa$

Now we have to calculate the solubility of this gaseous solute when its pressure is 79.39 kPa.

$C_{(79.39kPa)}=k_H\times p$

$C_{(79.39kPa)}=(6.52\times 10^{-7}g/mL.kPa)\times (79.39kPa)$

$C_{(79.39kPa)}=5.18\times 10^{-5}g/mL$

Therefore, the solubility of this gaseous solute will be, $5.18\times 10^{-5}g/mL$

7 0

3 years ago

A 15.00-ml sample of a naoh solution of unknown concentration requires 17.88 ml of a 0.1053 m h2so4 solution to reach the equiva

Sergeu [11.5K]

Answer:

0.1255 M

Explanation:

1) Data:

Base: NaOH

Vb = 15.00 ml = 15.00 / 1,000 liter

Mb = ?

Acid: H₂SO₄

Va = 17.88 ml = 17.88 / 1,000 liter

Ma = 0.1053

2) Chemical reaction:

The titration is an acid-base (neutralization) reaction to yield a salt and water:

Acid + Base → Salt + Water

H₂SO₄ (aq) + NaOH(aq) → Na₂SO₄ (aq) + H₂O (l)

3) Balanced chemical equation:

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

Placing coefficient 2 in front of NaOH and H₂O balances the equation

4) Stoichiometric mole ratio:

The coefficients of the balanced chemical equation show that 1 mole of H₂SO₄ react with 2 moles of NaOH. Hence, the mole ratio is:

1 mole H₂SO₄ : 2 mole NaOH

5) Calculations:

a) Molarity formula: M = n / V (in liter)

⇒ n = M × V

b) Nunber of moles of acid:

nₐ = Ma × Va = 0.1053 (17.88 / 1,000)

c) Number of moles of base, nb:

nb = Mb × Vb = Mb × (15.00 / 1,000)

d) At equivalence point number of moles of acid = number of moles of base

nₐ = nb

0.1053 × (17.88 / 1,000) = Mb × (15.00 / 1,000)

Mb = 0.1053 × 17.88 / 15.00 = 0.1255 mole/liter = 0.1255 M

3 0

3 years ago

Read 2 more answers

How many grams of H2 are needed to react with 2.40 g of N2?

Georgia [21]

Is there an equation? I can't help if there's no equation involved.

5 0

3 years ago

hydrogen decomposes quickly when exposed to light. the reaction for decomposing hydrogen peroxide is:

Svet_ta [14]

The decomposition reaction for hydrogen peroxide is given below:

2 $H_{2}$ $O_{2}$ → 2 $H_{2}$ O + $O_{2}$

This is a decomposition reaction.

Reactions in which a reactant breaks into two or more products are known as Decomposition reactions.

AB → A + B

here, AB represents the reactant that begins the reaction, and A and B represent the products of the reaction

The decomposition reaction of decomposing hydrogen peroxide is exothermic. When the hydrogen peroxide undergoes a decomposition reaction, heat is also released along with water and oxygen.

Hence the reaction for decomposing hydrogen peroxide is :

2 $H_{2}$ $O_{2}$ → 2 $H_{2}$ O + $O_{2}$

If you need to learn more about Decomposition reaction, click here

brainly.com/question/16987748?

#SPJ4

5 0

8 months ago

A student attempts to measure the specific heat capacity of an unknown liquid through repeated trials. She measures its specific

Goryan [66]

Answer:

2.13

Explanation:

4 0

3 years ago