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2 years ago

What is the scientific definition of heat

Chemistry

1 answer:

Usimov [2.4K]2 years ago

4 0

Answer:

Most of us use the word 'heat' to mean something that feels warm, but science defines heat as the flow of energy from a warm object to a cooler object.

Explanation:

Heat energy is the result of the movement of tiny particles called atoms, molecules or ions in solids, liquids and gases.

At a molecular level, heat is the transfer of energy that makes use of or stimulates disorderly molecular motion in the surroundings.

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combustion analysis of an unknown compound provides the following data: 73.5 grams carbon (C), 4.20 grams hydrogen (H) and 72.3

Alex17521 [72]

M(C)=73.5 g
m(H)=4.20 g
m(Cl)=72.3 g

mass of compound
m=m(C)+m(H)+m(Cl)

m=73.5+4.20+72.3=150 g

w(H)=100m(H)/m
w(H)=100*4.20/150=2.8%

w(Cl)=100m(Cl)/m
w(Cl)=100*72.3/150=48.2%

w(C)=100-w(H)-w(Cl)
w(C)=100-2.8-48.2=49.0%

4 0

3 years ago

Write a balanced equation for the combustion of C7H16(l) (heptane) -- i.e. its reaction with O2(g) forming the products CO2(g) a

JulsSmile [24]

Answer:

The standard enthalpy of reaction = -4854.7kJ

The difference: ΔH-ΔE = Δ(PV) = Δn.R.T = 9910.288 J ≈ 9.91 kJ

Explanation:

The balanced chemical equation for the combustion of heptane:

C₇H₁₆ (l) + 11 O₂ (g) → 7 CO₂ (g) + 8 H₂O (l)

Given: The standard enthalpy of formation ( $\Delta H _{f}^{\circ }$ ) for: C₇H₁₆ (l) = -187.8 kJ/mol, O₂ (g) = 0 kJ/mol, CO₂ (g) = -393.5 kJ/mol, H₂O (l) = -286 kJ/mol

To calculate the standard enthalpy of reaction ( $\Delta H _{r}^{\circ }$ ) can be calculated by the Hess's law:

$\Delta H _{r}^{\circ } = \left [\sum \nu \cdot\Delta H _{f}^{\circ }(products) \right ] - \left [\sum \nu\cdot\Delta H _{f}^{\circ }(reactants) \right ]$

Here, $\nu$ is the stoichiometric coefficient

⇒ $\Delta H _{r}^{\circ } =$

$\left [ 7\times \Delta H _{f}^{\circ }\left (CO_{2}\right )+ 8\times \Delta H _{f}^{\circ }\left (H_{2}O \right )\right ]$

$- \left [1\times \Delta H _{f}^{\circ }\left (C_{7}H_{16}\right ) +11\times \Delta H _{f}^{\circ }\left (O_{2} \right ) \right ]$

$=\left [ 7\times \left (-393.5 kJ/mol \right )+ 8\times \left (-286 kJ/mol \right )\right ]$

$-\left [1\times \left (-187.8 kJ/mol \right ) +11\times \left (0 kJ/mol \right ) \right ]$

⇒ $\Delta H _{r}^{\circ } = \left [ \left (-2754.5 \right )+ \left (-2288 \right )\right ]\left -[ \left (-187.8 \right ) +\left (0 \right )\right ]$

⇒ $\Delta H _{r}^{\circ } = \left [ -5042.5 ]\left -[ -187.8] = \left ( -4854.7kJ \right )$

To calculate the difference: ΔH-ΔE=Δ(PV)

We use the ideal gas equation: P.V = n.R.T

⇒ ΔH-ΔE=Δ(PV) = Δn.R.T

Given: Temperature:T = 298K, R = 8.314 J⋅K⁻¹⋅mol⁻¹

Δn = number of moles of gaseous products - number of moles of gaseous reactants = (7)- (11) = (-4)

⇒ ΔH-ΔE=Δ(PV) = Δn.R.T = (-4 mol) × (8.314 J⋅K⁻¹⋅mol⁻¹) × (298K) = 9910.288 J = 9.91 kJ (∵ 1 kJ = 1000J )

8 0

3 years ago

What mineral property is illustrated by this photograph?

lbvjy [14]

<h2>Hardness, lustre, and colour.</h2>

Explanation:

These Rocks shown in photographs are made of different types of minerals which have properties as follows:

●The color of the rock is grey, brown and yellow after it is ground into a powder its color is streak.

● The lustre of the rock tells how shiny the rocks are.

● Other properties include hardness, texture, shape, and size.

7 0

3 years ago

Compute the value of the molar heat capacity at constant volume, CVCV, for CO2CO2 on the assumption that there is no vibrational

katovenus [111]

Answer:

Explanation:

Molar heat capacity at constant volume Cv of a gas = n x .5 R where n is degree of freedom of the gas molecules

CO₂ is a linear molecule , so number of degree of freedom = 3 + 2 = 5

3 is translational and 2 is rotational degree of freedom . There is no vibrational degree of freedom given .

So Cv = 5 / 2 R

= 2.5 R .

4 0

3 years ago

Andi performs the calculation that is shown below.

rodikova [14]

Answer: 3.59

Explanation:

(2.06)(1.743)(1.00)

2.06 × 1.743 × 1.00

= 3.59058

Two of the multiplied digits are represented in 3 significant figures. Therefore, for correct representation, the result of the product should be written to three significant figures.

3.59058 to 3 significant figures:

First three digits = 3.59

Fourth digit '0' is less than 5, and thus rounded to 0 with other succeeding digits

Therefore, (2.06)(1.743)(1.00) to 3 significant figures equals :

3.59

3 0

3 years ago

What is the scientific definition of heat​

What is the scientific definition of heat