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3 years ago

What is diffusion?Class 9th Chemistry

2 answers:

6 0

Diffusion is the movement of a substance from an area of high concentration to an area of low concentration . Diffusion happens in liquids and gases because their particles move randomly from place to place . Diffusion is an important process for living things ; it is how substances move in and out of cells .

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yawa3891 [41]3 years ago

4 0

Answer:

diffusion is a means of transport, which occurs through cells . for example exchange of gases that takes place in alveoli occurs due to diffusion.

Explanation:

in diffusion the object or fluid moves from region of higher concentration to the region of lower concentration.

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In an acid-base titration experiment, 50 mL of a 0.05 M solution of acetic acid (Ka= 1.75 x 10-5 ) was titrated with a 0.05M sol

Viktor [21]

Answer:

(3) 5.36

Explanation:

Since this is a titration of a weak acid before reaching equivalence point, we will have effectively a buffer solution. Then we can use the Henderson-Hasselbalch equation to answer this question.

The reaction is:

HAc + NaOH ⇒ NaAc + H₂O

V NaOH = 40 mL x 1 L/1000 mL = 0.040 L

mol NaOH reacted with HAc = 0.040 L x 0.05 mol/L = 0.002 mol

mol HAC originally present = 0.050 L x 0.05 mol/L = 0.0025 mol

mol HAc left after reaction = 0.0025 - 0.002 = 0.0005

Now that we have calculated the quantities of the weak acid and its conjugate base in the buffer, we just plug the values into the equation

pH = pKa + log ((Ac⁻)/(HAc))

(Notice we do not have to calculate the molarities of Ac⁻ and HAc because the volumes cancel in the quotient)

pH = -log (1.75 x 10⁻⁵) + log (0.002/0.0005) = 5.36

THe answer is 5.36

5 0

3 years ago

Read 2 more answers

Suppose you have 100 grams of radioactive plutonium-239 with a half-life of 24,000 years. how many grams of plutonium-239 will r

Alexandra [31]

To solve this problem, let us first calculate for the rate constant k using the half life formula:

t1/2 = ln 2 / k

where t1/2 = half life period = 24,000 years, therefore k is:

k = ln 2 / 24,000

k = 2.89 x 10^-5 / yr

Now we use the rate equation:

A = Ao e^(-k t)

where,

A = mass of Plutonium-239 after number of years

Ao = initial mass of Plutonium-239

t = number of years

A. t = 12,000 years, find A

A = 100g e^(- 2.89 x 10^-5 * 12,000)

A = 70.7 g

B. t = 24,000 years, find A

A = 100g e^(- 2.89 x 10^-5 * 24,000)

A = 50 g

C. t = 96,000 years, find A

A = 100g e^(- 2.89 x 10^-5 * 96,000)

A = 6.24 g

5 0

3 years ago

What volume of a 2.0M NaOH(aq) is needed to completely neutralize 24 milliliters of 0.5M HCl(aq)?

borishaifa [10]

Answer:

$V_{base}=6.0mL$

Explanation:

Hello there!

In this case, by considering that the reaction between sodium hydroxide and hydrochloric acid is in a 1:1 mole ratio of these two reactants, we are able to use the following equation relating the concentration and volume of each one:

$M_{acid}V_{acid}=M_{base}V_{base}$

In such a way, by solving for the volume of the base, we will obtain:

$V_{base}=\frac{M_{acid}V_{acid}}{M_{base}} \\\\V_{base}=\frac{0.5M*24mL}{2.0M}\\\\V_{base}=6.0mL$

Regards!

8 0

3 years ago

2. A reaction vessel is charged with hydrogen iodide, which partially decomposes to molecular hydrogen and iodine:2HI (g) H2(g)

Deffense [45]

Answer:

The value of Kp at this temperature is 7.44*10⁻³

Explanation:

Chemical equilibrium is established when there are two opposite reactions that take place simultaneously at the same speed.

For the general chemical equation for a homogeneous gas phase system:

aA + bB ⇔ cC + dD

where a, b, c and d are the stoichiometric coefficients of compounds A, B, C and D, the equilibrium constant Kp is determined by the following expression:

$Kp=\frac{P_{C} ^{c} *P_{D} ^{d} }{P_{A} ^{a} *P_{B} ^{b} }$

Where Px is the partial pressure of each of the components once equilibrium has been reached and they are expressed in atmospheres. The equilibrium constant Kp depends solely on temperature and is dimensionless.

In the case of the reaction:

2 HI (g) ⇔ H₂ (g) + I₂ (g)

the equilibrium constant Kp is determined by the following expression:

$Kp=\frac{P_{H_{2} } *P_{I_{2} } }{P_{HI} ^{2} }$

The system comes to equilibrium at 425 °C, and

PHI = 0.794 atm
PH2 = 0.0685 atm
PI2 = 0.0685 atm

Replacing:

$Kp=\frac{0.0685*0.0685}{0.794^{2} }$

Kp=7.44*10⁻³

The value of Kp at this temperature is 7.44*10⁻³

4 0

3 years ago

What are the components of an electromagnet and how do they get connected?

Dmitriy789 [7]

Well I'm sure many a time you've seen on some science experiment someone wrap a copper wire around a nail well thats generally the idea for electromagnets you get a solid piece of iron which is the only metal that is magnetic and you wrap a copper wire around it and the idea is to make two opposing magnetic poles by aligning the molecules with a electrical charge (a battery) so now with all three pieces assembles you have a copper wire attached to two sides of a battery and wrapped around a nail

6 0

3 years ago

Read 2 more answers

What is diffusion?Class 9th Chemistry ​

What is diffusion?Class 9th Chemistry