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3 years ago

Match the following associations. Exothermic or endothermic

Chemistry

1 answer:

Alekssandra [29.7K]3 years ago

8 0

Answer:

1) ∆H is positive $\Rightarrow$ Endothermic

2) $E_p>E_r$ $\Rightarrow$ Endothermic

3) Energy is absorbed $\Rightarrow$ Endothermic

4) $E_r>E_p$ $\Rightarrow$ Exothermic

5) ∆H is negtive $\Rightarrow$ Exothermic

Explanation:

∆H is called as enthalpy change

It is also called as Heat of reaction

Energy is required for the bond to break a bond.

Energy is released when a bond is formed.

$H_2+Cl_2>2HCl$

that is

$H-H+Cl-Cl>2H-Cl$

We see in this equation, bonds between hydrogen and chlorine molecules gets broken and on the right side bond is formed in HCl.

If energy of products greater than energy of reactants then the reaction enthalpy change is endothermic .

If energy of products lesser than energy of reactants then the reaction enthalpy change is exothermic .

For example

$\Delta H=E_p-E_r$

$=30KJ-20KJ$

$=+10KJ$

(positive hence endothermic)

$\Delta H=E_p-E_r$

$=10KJ-40KJ$

$=-30KJ$

(negative hence exothermic)

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At room temperature (20°C} and pressure, the density of air is 1.189 g/L. An object will float in air if its density is less tha

Alekssandra [29.7K]

Explanation:

$Density =\frac{Mass}[Volume}$

Density of the air ,d= 1.189 g/L

(a) Density of the evacuated ball

Mass of the ball ,m = 0.12 g

Volume of the ball = $V=560 cm^3=560 ml=0.560 L$

$D =\frac{0.12 g}{0.560 L}=0.214 g/L$

D<d, teh evacuated ball will flaot in air.

(b) Density of the evacuated ball D = 0.214 g/L

Density of carbon dioxide gas = $d_1=1.830 g/L$

Mass of the carbon dioxide gas :

$1.830 g/L\times 0.560 L=1.0248 g$

Total density of filled ball with carbon dioxide gas:

$\frac{0.12 g+1.0248 g}{0.560 L}==2.044 g/L$

The ball filled with carbon dioxide will not float in the air because total density of filled ball is greater than the density of an air.

(c) Density of the evacuated ball D = 0.214 g/L

Density of hydrogen gas = $d_2=0.0899 g/L$

Mass of the hydrogen gas :

$1.830 g/L\times 0.560 L=0.050344 g$

Total density of filled ball with hydrogen gas:

$\frac{0.12 g+0.050344 g}{0.560 L}==0.3041 g/L$

The ball filled with hydrogen will float in the air because total density of filled ball is lessor than the density of an air.

(d) Density of the evacuated ball D = 0.214 g/L

Density of oxygen gas = $d_3=1.330 g/L$

Mass of the oxygen gas :

$1.330 g/L\times 0.560 L=1.7448 g$

Total density of filled ball with oxygen gas:

$\frac{0.12 g+1.7448 g}{0.560 L}=1.5442 g/L$

The ball filled with oxygen will not float in the air because total density of filled ball is greater than the density of an air.

(e) Density of the evacuated ball D = 0.214 g/L

Density of nitrogen gas = $d_4=1.165 g/L$

Mass of the nitrogen gas :

$1.165 g/L\times 0.560 L=0.6524 g$

Total density of filled ball with nitrogen gas:

$\frac{0.12 g+0.6524 g}{0.560 L}==1.3792 g/L$

The ball filled with nitrogen will not float in the air because total density of filled ball is greater than the density of an air.

f) Mass must be added to sink the ball = m

Density of ball > Density of the air ; to sink the ball.

$\frac{0.12g +m}{0.560L}>1.189 g/L$

m > 0.54584 g

For any case weight added to ball to make it sink in an air should be grater than the value of 0.54584 grams.

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2 years ago

Explain, in terms of element classification, why KBr is an ionic compound

enot [183]

LBr is ionic compound because k for potassium is metal which means it’s on the left side of the periodic table and Br which is bromine is a non metal which means is on the right side of the periodic table.

In Conclusion when a non metal and metal come together the are called ionic compound

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3 years ago

Janice bought 40 shares of stock at $31.82 per share. She received dividends of $1.11 per share for 1 year. (Do not use commas,

Alborosie

Answer:

$30.71 per share

Explanation:

The purchase price is what Janice invested for every share.

Since the stock was priced at $31.82 per share and she received a $1.11 dividend per share, her investment was:

$31.82 - $1.11 = $30.71 per share ← answer

This price is the cost for Janice, over which she shall calculate their returns (gains or losses) on the future, when she sells the shares, for instance.

The total investment of Janice was the number of shares multipled by the purchase price:

40 shares × ($31.82 - $1.11)/ share

40 shares × ($30.71) / share = $1,228.40 (total investment)

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2 years ago

State ten important of osmosis?

algol [13]

Explanation:

Osmosis is the movement of water molecules, across a semipermeable membrane, from a hypotonic solution to a hypertonic solution

Osmosis is critical in the maintenance of the right amount of water in the cells an organism. Water is a universal solvent and is especially important for biochemical activities of a cell. Osmosis maintains the right water homeostasis in cells.

Osmosis is useful in the absorption of water by the roots of the plants and the maintenance of transpirational pull that ensures herbecious plants remain upright.

Osmosis enables the opening and closing of plant stomata hence regulating the loss of water by the plants.

Learn More:

For more on osmosis check out;

brainly.com/question/6199270

brainly.com/question/6320563

#LearnWithBrainly

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2 years ago

Observation or inference The container is filled to the 350 ml mark with water

Luba_88 [7]

Observation is acknowledging and noting some facts from the surroundings or the environment. Usually, observation is done using the five senses of human such as the sense of sight, sense of smell, sense of touch, sense of hearing and sense of tasting. It can also be qualitative and quantitative. Qualitative observations are those who use non-numeric forms in expressing the observation however quantitative uses numeric forms in presenting the observation. Inference on the other hand is the probable explanation or interpretation based on the observation given. Therefore, the statement "The container is filled to the 350 ml mark with water " is an observation.

8 0

2 years ago