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4 years ago

Most substances become less dense as the temperature increases. Which substance is an exception to this rule

Chemistry

2 answers:

stealth61 [152]4 years ago

6 0

The substance is water

oee [108]4 years ago

4 0

Answer : Ice at 0° C.

Explanation : The statement that most of the substances becomes less dense as the temperature increases is not true for ice.

As when the temperature increases the ice melts into liquid which is found to be more denser than ice. The mass is observed to be the same, but the volume decreases as the melting process occurs.

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How many grams of sodium acetate ( molar mass = 83.06 g/mol ) must be added to 1.00 Liter of a 0.200 M acetic acid solution to m

Pie

<u>Answer:</u> The mass of sodium acetate that must be added is 30.23 grams

<u>Explanation:</u>

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$

Molarity of acetic acid solution = 0.200 M

Volume of solution = 1 L

Putting values in above equation, we get:

$0.200M=\frac{\text{Moles of acetic acid}}{1L}\\\\\text{Moles of acetic acid}=(0.200mol/L\times 1L)=0.200mol$

To calculate the pH of acidic buffer, we use the equation given by Henderson Hasselbalch:

$pH=pK_a+\log(\frac{[\text{salt}]}{[\text{acid}]})$

$pH=pK_a+\log(\frac{[CH_3COONa]}{[CH_3COOH]})$

We are given:

$pK_a$ = negative logarithm of acid dissociation constant of acetic acid = 4.74

$[CH_3COONa]=?mol$

$[CH_3COOH]=0.200mol$

pH = 5.00

Putting values in above equation, we get:

$5=4.74+\log(\frac{[CH_3COONa]}{0.200})$

$[CH_3COONa]=0.364mol$

To calculate the mass of sodium acetate for given number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Molar mass of sodium acetate = 83.06 g/mol

Moles of sodium acetate = 0.364 moles

Putting values in above equation, we get:

$0.364mol=\frac{\text{Mass of sodium acetate}}{83.06g/mol}\\\\\text{Mass of sodium acetate}=(0.364mol\times 83.06g/mol)=30.23g$

Hence, the mass of sodium acetate that must be added is 30.23 grams

7 0

3 years ago

Help me pleaseee, if you do tyy :)

ruslelena [56]

There is one atom of sulfur :)

4 0

3 years ago

What explanation can you give for why the sodium-potassium pump does not run out of ions to move in or out of the cell

rewona [7]

The sodium-potassium pump does not run out of ions since ion exchange is essential for the action potential to take place and to maintain homeostasis.

The cell has variable concentrations of different substances compared to the environment that surrounds it, with significant differences with sodium and potassium.

The main function of the sodium-potassium pump is to maintain homeostasis of the intracellular medium, controlling the concentrations of these two ions.

In order to carry out the adequate exchange of sodium and potassium ions in the extra and intracellular medium, the cells need an active transport process that is carried out thanks to the sodium potassium pump.

This process is needed for the maintenance and functioning of cells, and it is essential for the action potential to be executed, necessary for the transmission of electrical impulses from neuron to neuron.

Therefore, we can conclude that the sodium potassium pump produces an exchange of potassium ions for sodium ions which keeps the cellular system functioning properly.

Learn more here: brainly.com/question/24336764

6 0

3 years ago

1. Calculate the number of moles of aluminum, sulfur, and oxygen atoms in 8.00 moles of aluminum sulfate, Al2(SO4)3. 2. Calculat

IgorLugansk [536]

Answer:

1) 16.0 moles Al

24.0 moles S

96.0 moles O

2)In 6.10 moles magnesium perchlorate, (Mg(CIO4)2 we have:

6.10 moles Mg

12.2 moles Cl

48.8 moles O

3)4.6 moles of propane (total) contains 13.8 moles of carbon and 36.8 moles of hydrogen atoms

4)The gold coin contains 7.8 *10^22 atoms

Explanation:

Step 1: Data given

Number of moles of aluminum sulfate, Al2(SO4)3 = 8.00 moles

Step 2: Calculate the number of moles

In 1 mol of aluminum sulfate, Al2(SO4)3 we have:

2 moles of Al

3 moles of S

12 moles of O

This means that in 8.00 moles of aluminum sulfate, Al2(SO4)3 we have:

2*8.00 = 16.0 moles Al

3*8.00 = 24.0 moles S

12*8 = 96.0 moles O

2. Calculate the number of moles of magnesium, chlorine, and oxygen atoms in 6.10 moles of magnesium perchlorate, (Mg(CIO4)2

1 mol of magnesium perchlorate, (Mg(CIO4)2 has:

1 Mol of Mg

2 moles of Cl

8 moles of O

In 6.10 moles magnesium perchlorate, (Mg(CIO4)2 we have:

1 * 6.10 moles = 6.10 moles Mg

2*6.10 = 12.2 moles Cl

8*6.10 = 48.8 moles O

3. A sample of propane, C3H8, contains 13.8 moles of carbon atoms. How many total moles of atoms does the sample contain?

In 1 mol of propane, C3H8 we have:

3 moles of C and 8 moles of H

This means if we have 13.8 moles of carbon, we have 13.8/3 = 4.6 moles of propane, C3H8 and 4.6 *8 = 36.8 moles of H

So 4.6 moles of propane contains 13.8 moles of carbon and 36.8 moles of hydrogen atoms

4. A rare gold coin (24 karat, or 100% gold) has a mass of 25.54 g. How many atoms of gold are present in this coin?

Calculate moles of gold:

Moles = mass of gold / molar mass gold

Moles = 25.54 grams / 196.97 g/mol

Moles = 0.1297 moles

Calculate atoms:

Number of atoms = moles * number of Avogadro

0.1297 * 6.022 *10^23 = 7.8 *10^22 atoms

The gold coin contains 7.8 *10^22 atoms

6 0

3 years ago

Which compounds below share the same empirical formula?

Olenka [21]

D. CH and C2H2

Both compounds have the empirical formula CH. The trick is to see if you can multiply one compound by a number to turn it into the other. In this case, you can multiply CH by 2 to make C2H2.

6 0

3 years ago