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3 years ago

Substances which will glow in the dark after being exposed to sunlight are called:

Chemistry

2 answers:

DiKsa [7]3 years ago

7 0

Answer:

phosphorescent substances.

Explanation:

nordsb [41]3 years ago

6 0

It is called phosphorescent substances.

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Why is galvanized steel preferred for outdoor uses?

Marizza181 [45]

Galvanized steel is preferred for outdoor uses because it is ideal to prevent rotting/corrosion A steel will rot more quickly if it's exposed to a larger amount of oxygen and H2O , which will exist if we put it oudoor Coating the steel with additional zinc will slow down the process

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3 years ago

What are differences and similarities between pure substances and mixtures

Snezhnost [94]

Answer:

HELLO THERE!

I HOPE MY ANSWER WILL HELP YOU :)

Explanation:

There is this picture that helped me. I hope it helps you too.

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3 years ago

A gas mixture contains 10.0 mole% H2O (v) and 90.0 mole % N2. The gas temperature and absolute pressure at the start of each of

Rainbow [258]

Answer: (a). T = 38.2 °C (b). V = 1.3392 cm³ (c). ii and iii

Explanation:

this is quite easy to solve, i will give a step by step analysis to solving this problem.

(a). from the question we have that;

the Mole fraction of Nitrogen, yи₂ = 0.1

Also the Mole fraction of Water, yн₂o = 0.1

We know that the vapor pressure is equal to the partial pressure because the vapor tends to condense at due point.

ρн₂o = ṗн₂o

= yн₂oP = 0.1 × 500 mmHg = 50 mmHg

from using Antoine equation, we apply the equation

logρн₂o = A - B/C+T

T = B/(A - logρн₂o) - C

= 1730.63 / (8.07131 - log 50mmHg) - 223.426

T = 38.2 °C

We have that the temperature for the first drop of liquid form is 38.2 °C

(b). We have to calculate the total moles of gas mixture in a 30 litre flask;

n = PV/RT

n = [500(mmHG) × 30L] / [62.36(mmHGL/mol K) × 323.15K] = 0.744 mol

Moles of H₂O(v) is 0.1(0.744) = 0.0744 mol

Moles of N₂ is 0.9(0.744) = 0.6696 mol

we have that the moles of water condensed is 0.0744 mol i.e the water vapor in the flask is condensed

Vн₂o = 0.0744 × 18 / 1 (g/cm³)

Vн₂o = 1.3392 cm³

Therefore, the volume of the liquid water is 1.3392 cm³

(3). (ii) and (iii)

The absolute pressure of the gas and The partial pressure of water in the gas would change if the barometric pressure drops.

cheers i hope this helps!!!!

4 0

3 years ago

Hydrogen is unique among the elements because __________. 1. It has only one valence electron. 2. It is the only element that ca

Talja [164]

Answer:

3,4

Explanation:

Hydrogen has no other electron hence there is no screening of the valence electron by inner electrons. It is the lightest known element with a relative molecular mass of 2. Screening effect refers to the fact that inner or core electrons prevent the outermost electron from feeling the attractive force of the nucleus.

6 0

3 years ago

Using the equations 2 Sr(s) + O₂ (g) → 2 SrO (s) ∆H° = -1184 kJ/mol SrO (s) + CO₂ (g) → SrCO₃ (s) ∆H° = -234 kJ/mol CO₂ (g) → C(

kkurt [141]

Answer: The $\Delta H^o_{rxn}$ for the reaction is 72 kJ.

Explanation:

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

$2SrCO_3(s)\rightarrow 2Sr(s)+2C(s)+3O_2(g)$ $\Delta H^o_{rxn}=?$