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lesantik [10]
2 years ago
12

How many pounds of coal would you have to burn to generate enough heat to boil a 15 l kettle?

Chemistry
1 answer:
rjkz [21]2 years ago
7 0
Note that
The heating value of standard coal is about 30,080 kJ/kg
1 L of water has a mass of 1.0 kg

The mass of 15 L of water = 15 kg.
The latent heat of vaporization of water is about 2260 kJ/kg,
 The energy required to boil 15 L of water is
(2260 kJ/kg)*(15 kg) = 33900 kJ

The mass of coal required to provide this energy is
(33900 kJ)/(30080 kJ/kg) = 1.127 kg

Because 1 kg = 2.205 lb, the mass of coal required is
(1.127 kg)*(2.205 lb/kg) = 2.485 lb

Answer: 2.49 lb (nearest hundredth)

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marissa [1.9K]

Determining if an object will float or sink is based on the density of the object and also the density of the solution, the lower the density, more likely the object is to float, and if the density is higher, therefore the object is heavier and it will sink. In our question we have ebony wood with a density of 1.2, the only possible layer that this material can float is on Chloroform, that has a higher density, therefore the answer is letter A

6 0
1 year ago
Why do you think lone pairs of electrons create greater repulsion when located near other
Sedaia [141]

When there are lone pairs on the valence shell of the central atom in a molecule, the bond angle is decreased.

The shape of molecules depend on the number of electron pairs on the valence shell of the molecules. These electron pairs could be lone pairs or bond pairs. Lone pairs occupy more space around the central atom since it is attracted to only one nucleus compared to bond pairs which are attracted to two nuclei.

When lone pairs are present on the central atom in a molecule, they tend to "squeeze" the molecule thereby decreasing the bond angle in the molecule. Hence, presence of one or more lone pairs of electrons make the bond angles get smaller.

Learn more: brainly.com/question/10079361

5 0
2 years ago
What is the similarity and difference between the 4 seasons
faltersainse [42]

Answer:

light temperature weather

4 0
3 years ago
What is the voltage across a 100 ohm circuit element that draws a current of 1 A?
andrey2020 [161]

Answer:

8) 45 volt

9) 8 ohms

100 volt

Explanation:

using ohms law all through

  • V=IR

8) v = 3×15

9) R= 120/15

the last V=100×1

7 0
2 years ago
6) (a) Calculate the absorbance of the solution if its concentration is 0.0278 M and its molar extinction coefficient is 35.9 L/
Anvisha [2.4K]

Answer:

6) (a) 0.499; (b) 31.7 %

7) 0.15

Explanation:

6) (a) Absorbance

Beer's Law is

A = \epsilon cl\\A = \text{35.9 L&\cdot$mol$^{-1}$cm$^{-1}$} $\times$ 0.0278 mol$\cdot$L$^{-1} \times $ 0.5 cm = \mathbf{0.499}

(b) Percent transmission

A = \log {\left (\dfrac{1}{T}}\right)}\\\\\%T = 100T\\\\T = \dfrac{\%T}{100}\\\\\dfrac{1}{T} = \dfrac{100 }{\%T}\\\\A = \log \left(\dfrac{100 }{\%T} \right ) = 2 - \log \%T\\\\0.499 = 2 - \log \%T\\\\\log \%T = 2 - 0.499 = 1.501\\\\\%T = 10^{1.501} = \mathbf{31.7}

7) Absorbance

A = \log \left (\dfrac{I_{0}}{I} \right ) = \log \left (\dfrac{I_{0}}{0.70I_{0}} \right ) = \log \left (\dfrac{1}{0.70} \right ) = -\log(0.70) = \mathbf{0.15}}

8 0
3 years ago
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