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kap26 [50]
3 years ago
9

____is used as anode for prevention of corrosion 1 aluminium 2 magnesium 3 iron

Chemistry
1 answer:
choli [55]3 years ago
7 0

Answer:

I'm not sure but I think the answer is Cathodic protection.

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A horizontal cylinder equipped with a frictionless piston contains 785 cm3 of steam at 400 K and 125 kPa pressure. A total of 83
guapka [62]

Answer:

a. 478.69 K

b. 939.43 cm^{3}

c. 19.30 J

d. 64.5J

Explanation:

From the question, we can identify the following;

V_{o} = 785cm^{3} = 0.000785 m^{3}

T_{o} = 400K

P_{o} = 125 Kpa =  125 000 Pa

Using the ideal gas equation,

PV = nRT

where R is the molar gas constant = 8.314 m^{3}⋅Pa⋅K^{-1}⋅mol^{-1}

Thus, n = PV/RT = (125000 × 0.000785)/(8.314 × 400) = 0.03 mol

a. Steam temperature in K

To calculate this, we use the constant pressure process;

q = nΔH

Where q is 83.8J according to the question

Thus;

83.8 = 0.03 × [34980 + 35.5T_{1} - (34980 + 35.5T_{o})]

83.8 = (0.03 × 35.5) (T_{1} - 400K)

83.8 = 1.065 (T_{1}  - 400)

78.69 = (T_{1}  - 400)

T_{1} = 400 + 78.69

T_{1}  = 478.69 K

b. Final cylinder volume

To calculate this, we make use of the Charles' law(Temperature and pressure are directly proportional)

V_{1}/T_{1} = V_{o}/T_{o}

V_{1}  =  V_{o}T_{1}/T_{o}

V_{1}   = (785 × 478.69)/400

V_{1}   = 939.43 cm^{3}

c. Work done by the system

Mathematically, the work done by the system is calculated as follows;

w = P(V_{1}- V_{o}) = 125 KPa ( 939.43 - 785) = 19.30 J

d. Change in internal energy of the steam in J

ΔU = q - w = 83.8 - 19.3 = 64.5J

6 0
3 years ago
A chemical equation is shown below. KNO3 → KNO2 + O2 What are the coefficients that should be added to balance this equation? Us
uysha [10]

20) Balanced chemical equation: 2KNO₃ → 2KNO₂ + O₂.

Potassium nitrate is decomposed on potassium nitrite and oxygen.

According to principle of mass conservation, number of atoms must be equal on both side of chemical reaction.  

There are two potassium atoms, two nitrogen atoms and six oxygen atoms on both side of balanced chemical reaction.  

Decomposition is reaction where one substance (in this example potassium nitrate) is broken down into two or more simpler substances (potassium nitrite and oxygen).  

21) The answer is:

Balanced chemical reaction: double recplacement reaction.

MgCl₂(aq) + Na₂CO₃(aq) → MgCO₃(s) + 2NaCl(aq).

The magnesium (Mg) and the sodium (Na) replace each other making this a double replacement reaction.

Reactivity series is an empirical progression of a series of metals, arranged by their reactivity from highest to lowest (alkaline metals have highest reactivity and Noble metals lowest reactivity):  

K > Ba > Sr > Na > Ca > Mg > Be > Al > Mn > Zn > Cr> Fe > Cd > Co > Ni > Sn > Pb > H(in acids) > Cu > Hg > Ag.

Metal higher in the reactivity series will displace another and it will be oxidized.

Magnesium is higher it this series than aluminium and aluminium is higher than copper.

22) The answer is: half life is 22 years.

Half-life is the time required for a quantity (in this example mass of the element) to reduce to half its initial value and is independent of initial concentration.

Mass of the element is reduced by half in 22 years from 45 grams to 22.5 grams.

First calculate the radioactive decay rate constant λ:

λ = 0.693 ÷ t.

λ  = 0.693 ÷ 22 y.

λ = 0.0315 1/y.

ln(m/m₀) = -λ·t₁.

ln(4.8125/308) = -0.0315 1/y · t₁.

t₁ = 132.02 y.

7 0
3 years ago
When 10.0 grams of ch4 reacts completely with 40.0 grams of o2 such that there are no reactants left over, 27.5 grams of carbon
Zina [86]

The balanced equation for the reaction is :-

CH₄(g) + 2O₂(g)  ---------> CO₂(g) + 2H₂O(l)

Molar mass of CH₄ = 16 g/mole

Molar mass of O₂ = 32 g/mole

Molar mass of H₂O = 18 g/mole

Molar mass of CO₂ = 44 g/mole

Now we calculate the number of moles of reactants,

moles of CH₄ = mass of CH₄/molar mass of CH₄ = 10/16 = 0.625

Moles of O₂ = mass of O₂/molar mass of O₂ = 40/32 = 1.25

Now, as per the balanced reaction, for complete reaction to occur, one mole of CH₄ require 2 moles of O₂

Thus, 0.625 moles of CH₄ requires 1.25 moles of O₂

both CH₄ and O₂ are present in the exact required quantity.

Hence, moles of CO₂ formed = moles of CH₄ reacted = 0.625

Mass of CO₂ formed = moles of CO₂ x Molar mass of CO₂ = 0.625 x 44 = 27.5g

Moles of H₂O formed = moles of O₂ reacted = 1.25g

<span>Thus, mass of H</span>₂O formed = moles of H₂O x molar mass of H₂O = 1.25 x 18 = 22.5g

8 0
3 years ago
Light acts like a
8_murik_8 [283]
Particle
wave are the words you're looking for to fill in the blanks
7 0
3 years ago
Read 2 more answers
5. What is the distance of something from side to side?
Sav [38]

Answer:

Distance of something it can be any type of distance

6 0
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