All categories

3 years ago

If you are doing a science experiment where you find out which liquid evaporates the fastest, will you have a control group?

2 answers:

7 0

Yes there will be a control group. It is the amount of water that you use. BTW can I have the brainiest answer. PLEASE....

dezoksy [38]3 years ago

4 0

No water would be your control.

You might be interested in

Force exerted on a lever is applied on the lever's

Cerrena [4.2K]

A force called the effort force is applied at one point on the lever in order to move an object, known as the resistance force, located at some other point on the lever

7 0

2 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

During a change of state, the temperature of a substance _____.

Natali5045456 [20]

Hello,

Your questions states:

During a change of state, the temperature of a substance _____?

In which you gave us some choices:

A. decreases if the arrangement of particles in the substance changes.
B. remains constant until the change of state is complete.
C. increases if the kinetic energy of the particles in the substance increases.
D. increases during melting and vaporization and decreases during freezing and condensation.

Your answer would be:

B. remains constant until the change of state is complete.

Your explanation/Reasoning:

It absorbs the energy, then after the phase changes it then increases the temperature all over again.

Have a nice day:)

Hope this helps!

~Rendorforestmusic

4 0

3 years ago

Read 2 more answers

Someone help me with this asap for 5p points and BRAINLIEST THANK YOU

GaryK [48]

Answer:

High trainability allows the owner to train the dog to handle certain things--some dog can be trained as police dogs and can be taught various jobs, so high trainability is very important

When a dog is Viscous, the dog will keep people away from your house, they will be able to keep danger away and because they are viscous they will be able to handle danger.

Loud bark- A loud bark from a dog can help alert other people when there is a intruder, it makes alot of noise so they can attract attention easily.

Quiet Bark- Ideal for pet owners who do not like noise, they bark quietly so they are not a bother to work or anyone doing something.

7 0

2 years ago

Strigol is an important plant hormone that is released by crops such as rice and sugarcane. Unfortunately for these plants, stri

Len [333]

The hydrogen deficiency index( HDI) of strigol is = 10

<h3>How to calculate HDI:</h3>

The hydrogen deficiency index is used to measure the number of degree of unsaturation of an organic compound.

Strigol is an example of an organic compound because it contains carbons and hydrogen.

To calculate the HDI using the molecular formula given (C19H20O6) the formula for HDI is used which is:

$hdi = \frac{1}{2} (2c + 2 + n - h - x)$

where C = number of carbon atoms = 19

n= number of nitrogen atoms = 0

h= number of hydrogen atoms = 20

X = number of halogen atoms = 0

Note that oxygen was not considered because it forms two bonds and has no impact.

There for HDI =

$\frac{1}{2} (2 \times 19 + 2 + 0 - 20 - 0)$

HDI=

$\frac{1}{2} (40 - 20)$

HDI =

$\frac{1}{2} \times 20$

HDI = 10

Therefore, the hydrogen deficiency index of strigol is = 10

Learn more about unsaturated compounds here:

brainly.com/question/490531

7 0

2 years ago