Determine the number of significant figures in 400

What substance would you add to nahco3(aq) to form a buffer solution?

ira [324]

Buffer solution is made by mixing a weak acid with its conjugate base or weak base with its conjugate acid. NaHCO₃(aq) is a conjugate salt and also a conjugate base of H₂CO₃(aq) acid. Hence H₂CO₃(aq) should be added to make the buffer solution.

7 0

3 years ago

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A chemistry student weighs out 0.0975 g of acrylic acid (HCH2CHCO2) into a 250. mL volumetric flask and diluted to the mark with

Alex17521 [72]

Answer:

27.06 mL.

Explanation:

Firstly, we need to calculate the molarity of acrylic acid.

Molarity is the no. of moles of solute dissolved in a 1.0 L of the solution.

M = (no. of moles of acrylic acid)/(V of the solution (L))

M = (mass/molar mass)acrylic acid / (V of the solution (L))

mass of acrylic acid = 0.0975 g, molar mass of acrylic acid = 72.06 g/mol, V of the solution = 250 mL = 0.25 L.

∴ M = (0.0975 g/72.06 g/mol)/(0.25 L) = 0.0054 M.

For the acid-base neutralization, we have the role:

The no. of millimoles of acid is equal to that of the base at the neutralization.

<em>∴ (XMV) NaOH = (XMV) acrylic acid.</em>

X is the no. of reproducible H⁺ (for acid) or OH⁻ (for base),

M is the molarity.

V is the volume.

For NaOH:

X = 1, M = 0.05 M, V = ??? mL.

For acrylic acid:

X = 1, M = 0.0054 M, V = 250.0 mL.

∴ V of NaOH = (XMV) acrylic acid/(XM) NaOH = (1)(0.0054 M)(250.0 mL)/(1)(0.05 M) = 27.06 mL.

8 0

3 years ago

a water heater contains 58 Gal of water. How many kilowatt-hours of energy are necessary to heat the water in the water heater b

Citrus2011 [14]

Answer:

6.45 KWh

Explanation:

Data given:

amount of water = 58 gallon

Convert gallons to L

1 gallon = 3.78541 L

58 gallon = 58 x 3.78541 = 220 L

change in temperature = 25 °C

kilowatt-hours of energy = ?

Solution:

First we have to change volume of water into mass

following formula will use

m = d x v . . . . . . (1)

as we know

density of water = 1000 g/L

Put values in equation 1

m = 1000 g/L x 220 L

m = 220000

To calculate heat we use following formula

Q = m.c.ΔT . . . . . . . . . . (2)

Where

m= mass

c = specific heat of water

specific heat of water = 4.186 J/g °C

ΔT = change in temperature

Put values in equation 1

Q = 220,000 g x 4.186 J/g °C x 25 °C

Q = 23023000 J

As we need this value in kilowatt-hours of energy so we convert J to KWh

1 J = 2.8 x 10⁻⁷ KWh

23023000 J = X KWh

Do cross multiplication

KWh = 23023000 J x 2.8 x 10⁻⁷ KWh / 1 J

KWh = 6.45 KWh

6.45 KWh (kilowatt-hours) of energy are needed to heat the water in the water heater.

3 0

3 years ago

An ice skater moves back and forth on an ice rink. She speeds up on the straight portion of the rink. She slows down near each e

andrey2020 [161]

The options are;

A) The skater experiences acceleration both while skating in a straight line and while making her turn.

B) Because the skater does not change her direction or speed, she does not experience acceleration.

C) The skater only experiences acceleration when she is turning.

D) The skater only experiences acceleration while skating in a straight line.

Answer:

A: The skater experiences acceleration both while skating in a straight line and while making her turn

Explanation:

We are told that She speeds up on the straight portion of the rink. This means that she experienced an acceleration since the speed was not constant but gradually increasing.

Also, we are told that She slows down near each end of the rink and then turns around. This means that she reduced speed before turning and it means there was also an acceleration as well when making the turn.

Thus, she experience acceleration both in the straight line and when making turn.

Option A is correct

6 0

3 years ago

How many polar bonds are found in this molecule

Law Incorporation [45]

A bond is non polar if it is between same atoms and polar if it is between different atoms.

Same atoms are like two dogs of same strength pulling a bone towards towards each other. But when it’s different atoms it’s like a big dog and small dog then the bone is more towards bigger dog. So it’s the same way in bonds.

Bonds are made up of electrons, when the more stronger pulling atom is present than other the electrons are more towards it and as a result we have polar bond. There is development of a kind of a negative pole and a positive pole.

The stronger atom has electrons towards itself so it has a little more negative charge while the other atom has positive charge. This makes bond polar.

So just look for bond between two different atoms, it would be polar.

Look at the pic below to see the answer.

Marked with green is bond between same atoms... one carbon and another carbon so it is not polar and test marked with blue are polar.

Well the answer should have been 10 but since the bonds at 3 and 8 are two of same type we count only one of them.

The answer is 8... well the answer should be 10 otherwise... discuss it with ur teacher

6 0

3 years ago