All categories

2 years ago

What is the molality of a solution that has 30mg of K3PO4 dissolved in 40mL of water? (The density of water is 1.00 g/mL)

Chemistry

1 answer:

sweet [91]2 years ago

8 0

Answer:

m = 0.0035 m.

Explanation:

Hello there!

In this case, since the formula for the computation of the molality is:

$m=\frac{n_{solute}}{m_{solvent}}$

We can first compute the moles of solute, K3PO4 by using its molar mass:

$n=30mgK_3PO_4*\frac{1gK_3PO_4}{1000gK_3PO_4}*\frac{1molK_3PO_4}{212.27gK_3PO_4} =1.41x10^{-4}mol$

Next, since the volume of water is 40.0 mL and its density is 1.00 g/mL we infer we have the same grams (40.0 g). Thus, we obtain the following molality by making sure we use the mass of water in kilograms (0.04000kg):

$m=\frac{1.41x10^{-4}mol}{0.0400kg}\\\\m=0.0035m$

In molal units (m=mol/kg).

Best regards!

You might be interested in

Escoge uno de los derechos de la siguiente lista que están Escogidos en el código de la niñez y adolescencia escribe en una hoja

Lera25 [3.4K]

Answer:

Hehe I don't know spanish -

Explanation:

6 0

2 years ago

Sodium hydroxide reacts with aluminum and water to produce hydrogen gas: 2 Al(s) + 2 NaOH(aq) + 6 H2O(l) → 2 NaAl(OH)4(aq) + 3 H

lianna [129]

Answer:

The mass of hydrogen gas formed is 0.205 grams

Explanation:

Step 1: Data given

Mass of 1.83 grams of Al

Mass of NaOH = 4.30 grams

Molar mass of Al = 26.98 g/mol

Molar mass of NaOH = 40 g/mol

Step 2: The balanced equation:

2 Al(s) + 2 NaOH(aq) + 6 H2O(l) → 2 NaAl(OH)4(aq) + 3 H2(g)

Step 3: Calculate moles of Al

Moles Al = mass Al / Molar mass Al

Moles Al = 1.83 grams / 26.98 g/mol

Moles Al = 0.0678 moles

Step 4: Calculate moles of NaOH

Moles NaOH = 4.30 grams / 40 g/mol

Moles NaOH = 0.1075 moles

Step 5: Calculate limiting reactant

For 2 moles of Al, we need 2 moles of NaOH

Aluminium is the limiting reactant. It will completely be consumed ( 0.0678 moles)

NaOH is in excess. There will react 0.0678 moles

There will remain 0.1075 - 0.0678 = 0.0397 moles

Step 6: Calculate moles of hydrogen

For 2 moles of Al, we need 2 moles of NaOH, to produce 3 moles of hydrogen

For 0.0678 moles of Al, there is produced 0.0678 *3/2 = 0.1017 moles of H2

Step 7: Calculate mass of H2

Mass of H2 = Moles H2 * Molar mass of H2

Mass of H2 = 0.1017 moles * 2.02 g/mol

Mass of H2 = 0.205 grams

The mass of hydrogen gas formed is 0.205 grams

6 0

3 years ago

1. How much 6.0 M HNO3 is needed to neutralize 39 mL of 2.0 M KOH?

quester [9]

Answer:

For 2. the answer is 15.0 mL

For other examples, you can solve by exact way as I have solved the 2nd example.

I have writen down all the balanced chemical reaction equation for examples 1, 3, 4, 5 for you. ( picture 2 )

Explanation:

Please see the step-by-step solution in the picture attached below.(picture 1)

Hope this answer can help you. Have a nice day!

6 0

3 years ago

At equilibrium, ________. At equilibrium, ________. all chemical reactions have ceased the rate constants of the forward and rev

balandron [24]

Answer:

At equilibrium, the rate of the forward, and the reverse reactions are equal.

Explanation:

In an equilibrium chemical reaction, the rate of forward reaction, is equal to the rate of reverse reaction. Note that the reactions does not cease at equilibrium, but rather, the reactants are converted to product, at the same rate at which the product is also being converted into the reactants in the reaction. When chemical equilibrium is reached, a careful calculation of the value of equilibrium constant is approximately equal to 1.

NB: If the value of equilibrium constant is far far greater than 1, then the reaction will favors more of the forward reaction, and if far far less than 1, the reaction will favor more of the reverse reaction.

6 0

3 years ago

What happens in a chemical change that does not occur in a physical change?

Andrej [43]

Answer:

In a chemical reaction, there is a change in the composition of the substances in question; in a physical change there is a difference in the appearance, smell, or simple display of a sample of matter without a change in composition. Although we call them physical "reactions," no reaction is actually occurring.

6 0

3 years ago