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Lubov Fominskaja [6]
3 years ago
15

Yasir wants to determine if there is a relationship between room color and sleep. Based on his research, Yasir makes an educated

guess that people fall asleep more quickly in a room painted blue than in a room painted yellow. He asks several people which color they like better -yellow or blue- and uses their responses to determine if his educated guess was correct. What is missing from Yasir’s scientific investigation?
A testable hypothesis that is based on research
An experiment that directly tests the hypothesis
Variables to be tested by an experiment Research on the topic to see what others have learned
Chemistry
2 answers:
kondaur [170]3 years ago
5 0

Answer:

Variables to be tested by an experiment Research on the topic to see what others have learned

Explanation:

Given that Yasir wants to determine if there is a relationship between room color and sleep. Based on his research, Yasir makes an educated guess that people fall asleep more quickly in a room painted blue than in a room painted yellow. He asks several people which color they like better -yellow or blue- and uses their responses to determine if his educated guess was correct.

The problem in his study is he really did not check the fact but depended on the reply of the people what the like

Sleep is different form liking a colour

Thus he should have recorded the paint colour and hours of sleep for a sample of reasonable size to test his hypothesis.

Variables to be tested by an experiment Research on the topic to see what others have learned is right answer

Fynjy0 [20]3 years ago
3 0

Yasir wanted to study the relationship between sleep and room color. So he has done all the background study required on the topic and arrived at a hypothesis that people fall asleep more rapidly in a room painted in blue color than in a room painted yellow. Yasir inquired several people which color they like better -yellow or blue- and used their feedback to decide whether his hypothesis was correct. There was no experiment conducted to observe the effect of a room color on sleep and the variables to be tested in the experiment were not properly identified.

Therefore, the correct answer would be,

An experiment that directly tests the hypothesis

Variables to be tested by an experiment

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the volume of a gas is 550 ml at 960 mm hg and 200.0°C. What volume would the pressure of the gas be 830 mm Hg if the temperatur
gavmur [86]

Answer:

V₂ = 568.9 mL

Explanation:

Given data:

Volume of gas = 550 mL

Pressure of a gas = 960 mmHg

Temperature = 200.0°C ( 200+273 = 473 K)

Final volume = ?

Final pressure = 830 mmHg

Final temperature = 150°C (150+273 = 423 K)

Solution:

Formula:  

P₁V₁/T₁ = P₂V₂/T₂  

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

Solution:

V₂ = P₁V₁ T₂/ T₁ P₂  

V₂ = 960 mmHg × 550 mL × 423 K / 473 K ×830 mmHg

V₂ = 223344000 mL / 392590

V₂ = 568.9 mL

8 0
3 years ago
Hydrogen and Methanol have both been proposed as alternatives to hydrocarbon fuels. Write balanced reactions for the complete co
Arlecino [84]

Answer:

The order of energy released per mass is

CH₃OH (-2.268 × 10⁴ kJ/kg) < C₈H₁₈ (-4.826 × 10⁴ kJ/kg) < H₂ (-2.835 × 10⁵ kJ/kg)

Explanation:

In order to calculate the enthalpy of a reaction (ΔH°r) we can use the following expression.

ΔH°r = ∑np × ΔH°f(p) - ∑nr × ΔH°f(r)

where

ΔH°f(i) are the enthalpies of formation of reactants and products

ni are the moles of reactants and products

<u>Combustion of hydrogen</u>

H₂(g) + 1/2 O₂(g) ⇒ H₂O(l)

ΔH°r = 2 mol × ΔH°f(H₂O) - 1 mol × ΔH°f(H₂) - 1/2 mol × ΔH°f(O₂)

ΔH°r = 2 mol × (-285.8 kJ/mol) - 1 mol × 0 - 1/2 mol × 0

ΔH°r = -571.6 kJ

571.6 kJ are released when 1 mole of H₂ is burned. The amount of heat released per kilogram is:

\frac{-571.6kJ}{1molH_{2}} .\frac{1molH_{2}}{2.016gH_{2}} .\frac{10^{3}gH_{2} }{1kgH_{2}} =-2.835 \times 10^{5} kJ/kgH_{2}

<u>Combustion of methanol</u>

CH₃OH(l) + 3/2 O₂(g) ⇒ CO₂(g) + 2 H₂O(l)

ΔH°r = 1 mol × ΔH°f(CO₂) + 2 mol × ΔH°f(H₂O) - 1 mol × ΔH°f(CH₃OH) - 3/2 mol × ΔH°f(O₂)

ΔH°r = 1 mol × (-393.5 kJ/mol) + 2 mol × (-285.8 kJ/mol) - 1 mol × (-238.4 kJ/mol) - 3/2 mol × 0

ΔH°r = -726.7 kJ

726.7 kJ are released when 1 mole of CH₃OH is burned. The amount of heat released per kilogram is:

\frac{-726.7kJ}{1molCH_{3}OH} .\frac{1molCH_{3}OH}{32.04gCH_{3}OH} .\frac{10^{3}gCH_{3}OH }{1kgCH_{3}OH} =-2.268 \times 10^{4} kJ/kgCH_{3}OH

<u>Combustion of octane</u>

C₈H₁₈(l) + 12.5 O₂(g) ⇒ 8 CO₂(g) + 9 H₂O(l)

ΔH°r = 8 mol × ΔH°f(CO₂) + 9 mol × ΔH°f(H₂O) - 1 mol × ΔH°f(C₈H₁₈) - 12.5 mol × ΔH°f(O₂)

ΔH°r = 8 mol × (-393.5 kJ/mol) + 9 mol × (-285.8 kJ/mol) - 1 mol × (-208.4 kJ/mol) - 12.5 mol × 0

ΔH°r = -5511.8 kJ

5511.8 kJ are released when 1 mole of C₈H₁₈ is burned. The amount of heat released per kilogram is:

\frac{-5511.8kJ}{1molC_{8}H_{18}} .\frac{1molC_{8}H_{18}}{114.2gC_{8}H_{18}} .\frac{10^{3}gC_{8}H_{18} }{1kgC_{8}H_{18}} =-4.826 \times 10^{4} kJ/kgC_{8}H_{18}

5 0
3 years ago
Chemistry test!!! no fake answers please and if you can explain then do it because I need all the help I can get!
ivanzaharov [21]

Answer:

(−ΔH°1)+12(−ΔH°2)+(ΔH°3)+(ΔH°4)

I hope this helps you out!! :)

8 0
3 years ago
A small 20-kg canoe is floating downriver at a speed of 2 m/s. What is the canoe’s kinetic energy?
Contact [7]

Hey [email protected]


EK = 1/2 * m * V²


Ek = 1/2 * 20 * 2²


Ek = 1 * 20 * 2² / 2


Ek = 80 / 2


Ek = 40 J


hope this helps!

7 0
3 years ago
Read 2 more answers
When a liquid is poured through a filter, what happens?
Anestetic [448]
The filter is a material with lots of tiny holes, that only the water can fit through. So flakes of leaf wont be in the water because it couldnt fit through the holes in the filter.

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