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harkovskaia [24]
3 years ago
15

Hot air at 80°C is blown over a 2-m by> on0 4-m flat surface at 30°C. If the average? convection heat transfer coefficient va

ries between 20 W/m2 °C and 100 W/m °C, draw a relation between the rate of heat transfer from the air to the 80°C Air 30°C plate.(nm kW) and the convection heat transfer coefficient
Chemistry
1 answer:
mars1129 [50]3 years ago
7 0

Explanation:

The given data is as follows.

       T_{air} = 80 ^{o}C,       T_{surface} = 30 ^{o}C

Area of the flat plate is 2 × 4 = 8 m^{2}.

Average convection heat transfer coefficient (h_(avg)) = \frac{(20 + 100) W/m^{2} ^{o}C}{2} = 60 W/m^{2} ^{o}C}.

Hence, formula to calculate heat transfer through convection from air to the water is given as follows.

                    q = h_{avg} \times A_{surface} \times (T_{air} - T_{surface})

                        = 60 W/m^{2} ^{o}C} \times 8 m^{2} \times [(80 - 30)]^{o}C

                        = 24000 W

or,                     = 24 kW

Hence, the direction of heat flow is from air to the surface.

Thus, we can conclude that transfer of heat is 24 kW.

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jonny [76]

Answer:

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Explanation:

Just some notes to help you:))

Covalent Bonds: A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons

5 0
3 years ago
Be sure to answer all parts. In the average adult male, the residual volume (RV) of the lungs, the volume of air remaining after
Alenkinab [10]

<u>Answer:</u>

<u>For a:</u> The number of moles of air present in the RV is 0.047 moles

<u>For b:</u> The number of molecules of gas is 2.83\times 10^{22}

<u>Explanation:</u>

  • <u>For a:</u>

To calculate the number of moles, we use the equation given by ideal gas follows:

PV=nRT

where,

P = pressure of the air = 1.00 atm

V = Volume of the air = 1200 mL = 1.2 L    (Conversion factor:  1 L = 1000 mL)

T = Temperature of the air = 37^oC=[37+273]K=310K

R = Gas constant = 0.0821\text{ L. atm }mol^{-1}K^{-1}

n = number of moles of air = ?

Putting values in above equation, we get:

1.00atm\times 1.2L=n_{air}\times 0.0821\text{ L atm }mol^{-1}K^{-1}\times 310K\\n_{air}=\frac{1.00\times 1.2}{0.0821\times 310}=0.047mol

Hence, the number of moles of air present in the RV is 0.047 moles

  • <u>For b:</u>

According to mole concept:

1 mole of a compound contains 6.022\times 10^{23} number of molecules.

So, 0.047 moles of air will contain (0.047\times 6.022\times 10^{23})=2.83\times 10^{22} number of gas molecules.

Hence, the number of molecules of gas is 2.83\times 10^{22}

7 0
3 years ago
Choose the term that best fits the following definition: the liquid or gas that carries the sample across the solid support.
iren [92.7K]

The correct answer is option B.

The liquid or gas that carries the sample across the solid support is called mobile phase.

In chromatography, there are two phases: mobile phase and solid phase.

The mobile phase can be either in gas form or liquid form.

While performing the chromatography technique, mobile phase moves over the stationary phase and its components adsorb to the stationary phase and set apart from each other at different rates.

In general, mobile phase refers to the solvent phase that slides over the stationary phase through the chromatography paper.

on the other hand, stationary phase is motionless.

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8 0
1 year ago
Which is formed by positive ions from a base and negative ions from an acid? a. Salt b. Vinegar
max2010maxim [7]

The formation of salt takes place by the sharing of positive ions from a base and negative ions from an acid.

This is based on the concept and principles of neutralization. The process of neutralization is the name of a chemical reaction between an acid and a base.

Hence, the correct option is a.

pH refers to a measure of how acidic or basic a solution is.

A pH is a measure of how basic or acidic a substance is. pH has a range of 0-14. A pH greater than 7 means the substance is basic.

A pH less than 7 means the substance is acidic. When the pH is exactly 7 that indicates that the substance is neutral.

Hence, the correct optiion is a.

The pH of a solution that has the same number of hydrogen ions as hydroxide ions is 7.

Hence, the correct option is c.

Baking soda has the greatest number of hydroxide ions.

Thus is because of the pH is 9. So, it will be more basic.

Hence, the correct option is a.

Hydrochloric acid will be least likely to completely dissolve in water.

Hence, the correct option is a.

Antacid is taken to get relieve from heartburn describes that the antacid is acidic and will raise the pH of the esophagus.

Hence, the correct option is c.

Acids measure below 7 describes the pH scale.

Hence, the correct option is a.

The order of these solutions from strong acid to strong base is  

Ammonia>battery acid>stomach acid>antacid>baking soda.

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3 0
10 months ago
Write this number using scientific notation:<br> 0.000735
bixtya [17]
0.000735 in scientific notation is 7.35 x 10^-4
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