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# Shing Hin

• ### Relative Concentrations

Reactant A undergoes dissociation into products B and C according to the following equilibrium reaction equationA(g)

B(g) + C(g)A rigid vessel, initially containing 0.072 mol/L of pure A, is allowed to equilibrate at 31°C.What would be the value of the equilibrium constant (Keq expressed in terms of the molar concentrations) if the equilibrium concentrations of all species are equal?

What would be the value of the equilibrium constant (Keq expressed in terms of the molar concentrations) if, at equilibrium, the concentration of A is 1.0% that of B?

(No units required.)

1 個解答化學9 年前
• ### Keq for a Gas-Phase Reaction

Keq for a Gas-Phase Reaction

A 7.00-L vessel contained 9.08×10-2 mol of gaseous PCl3, 1.02×10-1 mol of gaseous PCl5, and 1.02×10-1 mol of Cl2 gas at equilibrium at 223°C.

Calculate the value of Keq (expressed in terms of the molar concentrations) for the reactionPCl3(g) + Cl2(g)

PCl5(g)

1 個解答化學9 年前
• ### Mass, Volume and Keq

An equilibrium mixture, at 538°C in a 1618-mL container, involving the chemical systemN2(g) + 3H2(g)

2NH3(g)is found to contain 3.30 g of N2, 0.116 g of H2, and 0.0193 g of NH3. Calculate the equilibrium constant (Keq expressed in terms of the molar concentrations) at the given temperature.

Thanks

1 個解答化學9 年前
• ### Redox Reactions(Basic Aqueous)

Balance the following equations, using the oxidation number method, and enter the coefficients in the boxes.The coefficients must be the smallest possible integers.

1. HPbO2-+ Re+ OH-+ H2O

ReO4-+ Pb+ H2O+ OH-

Note that neither H2O nor OH- should appear on more than one side of the equation. Thus, some of the coefficients above must be 0.

2. I-+ OCl-+ OH-+ H2O

IO3-+ Cl-+ OH-+ H2O

Note that neither H2O nor OH- should appear on more than one side of the equation. Thus, some of the coefficients above must be 0.

1 個解答化學9 年前
• ### Balancing Redox Equations

Balancing Redox Equations

Balance the following equation, using the oxidation number method, and enter the coefficients in the boxes.

The coefficients must be the smallest possible integers.NaClO+ Cr(OH)3

Na2CrO4+ Cl2+ H2O+ NaOH

1 個解答化學9 年前
• ### Stoichiometry RedOx Reaction

1. Oxalic acid, H2C2O4, reacts with dichromate ion, in acidic solution to produce carbon dioxide and chromium(III) ion.

If exactly 50.0 mL of an oxalic acid solution is required to react completely with 85.0 mL of a 0.0450 M dichromate solution, what is the molarity of the oxalic acid solution?

2. Thiosulfate ion, S2O32-, reacts with iodine in acidic solution to produce tetrathionate ion, S4O62-, and iodide ion .

If exactly 50.0 mL of S2O32- solution is required to react completely with 45.0 mL of 7.50×10-4 M I2 solution, what is the molarity of the S2O32- solution?

1 個解答化學9 年前
• ### Chemistry Redox Reactions

Redox Reactions -- Electrons Transferred

Balance each of the following equations occuring in basic aqueous solution.

In each case find the number (n) of electrons transferred from the reducing agent to the oxidizing agent for the conventionally balanced equation (full reaction).

Cr2O3 + OCl-

MnO2 + CO32-

1 個解答化學9 年前
• ### Chemistry

What mass of the second-listed reactant in each of the following reactions is needed to react completely with 7.014 g of the first-listed reactant?CH4 + 4Cl2 → 4HCl + CCl4

SiO2 + 3C → 2CO + SiC

2 個解答化學9 年前
• ### Chemistry

Stoichiometry and Yields of a Decomposition Reaction

Ammonium dichromate decomposes according to the following reaction.(NH4)2Cr2O7

N2 + 4H2O + Cr2O3

What mass of H2O can be formed from the decomposition of 91.9 g of (NH4)2Cr2O7?

What mass of Cr2O3 can be formed from the decomposition of 91.9 g of (NH4)2Cr2O7?

What mass of N2 can be formed from the decomposition of 91.9 g of (NH4)2Cr2O7?

1 個解答化學9 年前
• ### Stoichiometry of 2step process

Consider the following two-step reaction sequence.

2NaCl + 2H2O

2NaOH + H2 + Cl2

2Fe + 3Cl2

2FeCl3

Assuming that all the chlorine generated in the first step is consumed in the second step, what mass of NaCl is needed in the first step to produce 13.2 g of FeCl3 in the second step?

1 個解答化學9 年前
• ### Limiting Reagent and % Yield

Under appropriate reaction conditions Al and S produce Al2S3 according to the equation2Al + 3S → Al2S3In a certain experiment with 22.1 g of Al and excess of S, a yield of 63.4% was obtained. What was the actual yield (i.e. mass) of Al2S3 obtained.

1 個解答化學9 年前
• ### Chemistry

Reaction Stoichiometry and Mass Ratios (two parts)

What mass of the second-listed reactant in each of the following reactions is needed to react completely with 6.913 g of the first-listed reactant?H2O2 + H2S → 2H2O + S

CH4 + 4Cl2 → 4HCl + CCl4

1 個解答化學9 年前
• ### Factorization

1. x3 - x2 + 3x - 3

2. x4 - 16

3. 3(x+2)2 - 12

4. u2 + 12u + 36

5. 3p2 - p - 4

1 個解答數學1 十年前
• ### Maths Question

1. Find the values of the constants A and B in the following identity.

Ax(x-1) + B(x-1)(x+1) 三 -x2 - x + 2

2 個解答數學1 十年前
• ### Probability Problem

1. A box contains 2 red, 2 black and 3 white balls. One ball is drawn randomly from the box. After putting the ball back into the box, one ball is again drawn randomly. Find the probability that

(a) the two balls drawn are both red;

(b) the two balls drawn are of the same color;

(c) the two balls drawn are of the different color.

THZ! =]

2 個解答數學1 十年前
• ### Probability Problem

In a stall game, the whole surface of a table is covered by square tiles of side 6cm as shown. A participant is asked to throw a metal disc of diameter 4cm onto the table. If the disc does not touch the side of any square, he wins. If it touches a side, he loses. Suppose a participant throws the disc and it stays on the table, what is the probability that he wins the game?

THZ!!

2 個解答數學1 十年前
• ### Probability Problems

1. A number is chosen at random from natural numbers 1 to 90. What are the probabilities of the following events?

(i) The number chosen is divisible by 3.

(ii) The number chosen is a multiple of 4.

(iii) The number has two digits which add up to 5.

THZ! =]

1 個解答數學1 十年前
• ### Multiplication of Probabilities Problems

1. Ken lives in Tuen Mun. He travels to school either by MTR or on foot. The probability of being late for school is 1/7 if he travels by MTR and 1/10 if he travels on foot.

a. Ken travels to school on foot on Monday, Tuesday and Wednesday. Find the probability that

(i) he will be late on Mon and Tue only in these three says;

(ii) he will be late on any two of these three days.

b. On Thursday, Ken goes to school to take part in a football match. If he is equally likely to travel by MTR or on foot, find the probability that he will be late on that day.

THX! =]

3 個解答數學1 十年前
• ### Maths Question (Symmetry & Transformation)

1.

a) If the point A(-2 , 1) is translated 5 units to the right to the point B, what are the coordinates of B?

b) When the point C is translated 3 units downward, it also reaches the point B. What are the coordinates of C?

2 個解答數學1 十年前
• ### Maths Question (Symmetry & Transformation)

1. L is a line in the rectangular coordinate plane parallel to the y-axis and it passes through a point M(-1,3).

a) If a point Q is the image when a point P(-2,-2) is reflected in L, find the coordinates of Q.

b) If a point R is the image when M is reflected in a horizontal line passing through Q in part(a), find the coordinates of R.

c) If a point S is the image when M is reflected in a vertical line passing through Q in part(a), find the coordinates of S.

2. Try to find ot a simple way for each of the following to transform the point A to the point B.\

a) A(3,5) , B(-1,-4)

b) A(-2,4) , B(2,-2)

c) A(2,5) , B(-5,2)

1 個解答數學1 十年前