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2 years ago

Iron in rock combining with oxygen to form hematite

Chemistry

1 answer:

blondinia [14]2 years ago

4 0

The answer is a. Chemical change.

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A coffee-cup calorimeter initially contains 125 g water at 24.28C. Potassium bromide (10.5 g), also at 24.28C, is added to the w

iren2701 [21]

Answer:

The solution is given below

Explanation:

Heat, q= mc∆T

q= 125g x 4.18 J/g∙°C x (21.18x- 24.28) °C

q= -1619.75J

NEGATIVE SIGN INDICATES THAT HEAT IS ABSORBED.

Enthalpy Change, ∆H = 1619.75 7/ 10.5 g

= 154.26 J/g

No. of moles of KBr = Mass of KBr/ Molecular Weight of KBr

=10.5g/119gmol-1

=0.088 mol

∆H= 1619.75 J/ 0.088 mol

= 18.41 kJ/mol

6 0

3 years ago

Air, with an initial absolute humidity of 0.016 kg water per kg dry air, is to be dehumidified for a drying process by an air co

amid [387]

Answer:

(a) The proportion of dry air bypassing the unit is 14.3%.

(b) The mass of water removed is 1.2 kg per 100 kg of dry air.

Explanation:

We can express the proportion of air that goes trough the air conditioning unit as $p_{d}$ and the proportion of air that is by-passed as $p_{bp}$ , being $p_{d}+p_{bp}=1$ .

The amount of water that goes into the drier inlet has to be 0.004 kg/kg, and can be expressed as:

$0.004 = 0.016*p_{bp}+ 0.002*p_{d}$

Replacing the first equation in the second one we have

$0.004 = 0.016*(1-p_{d})+ 0.002*p_{d}=0.016-0.016*p_{d}+0.002*p_{d}\\0.004 - 0.016 = (-0.016+0.002)*p_{d}\\-0.012 = -0.014*p_{d}\\p_{d}=\frac{-0.012}{-0.014}=0.857\\\\p_{bp}=1-p_{d}=1-0.857=0.143$

(b) Of every kg of dry air feed, 85.7% goes in to the air conditioning unit.

It takes (0.016-0.002)=0.014 kg water per kg dry air feeded.

The water removed of every 100 kg of dry air is

$100 kgDA*0.857*0.014 kgW/kgDA= 1.1998 \approx 1.2 kgW$

It can also be calculated as the difference in humiditiy between the inlet and the outlet: (0.016-0.004=0.012 kgW/kDA) and multypling by the total amount of feed (100 kgDA).

100 * 0.012 = 1.2 kgW

7 0

4 years ago

30 POINTS

soldi70 [24.7K]

Answer:

Answer below.

Explanation:

An exothermic reaction is a chemical reaction that releases energy through light or heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation: reactants → products + energy.

5 0

3 years ago

Ex 1) 45.2 g of Zn = _____ moles Zn<br><br> Ex 2) 0.568 moles Ag = _____ grams Ag

Jlenok [28]

the molar mass of Zn is 65

number of mole(n)=reacting mass/molar mass
n=45.2/65
=0.70g/mol

2.the molar mass of Ag is 108

0.568=m/108
then cross multiply
m=0.568×108
m=61.3g

5 0

3 years ago

How to go this problem

spin [16.1K]

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4 0

3 years ago