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Vsevolod [243]
3 years ago
13

How many grams of Na2CO3 must be dissolved into 155g of water to create a solution with a molarity of 8.20 mol/kg

Chemistry
1 answer:
zhannawk [14.2K]3 years ago
4 0

Answer:

135g Na2CO3

Explanation:

I'm going to assume you mean Molality which is mol solute/kg solvent

Molarity would be mol soute/ L solution

we know we have 155g of water which is .155 kg

essentially we have the equation:

mol/kg = 8.20

we substitute .155 in for kg and get:

mol/.155 = 8.20

Solving this  gives mol = 1.271

now we must convert to grams using the molar mass

Molar mass Na2CO3 = 106G/mol

so to cancel moles we multiply:

1.271mol x 106g/mol

= 135g

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A water treatment plant applies chlorine for disinfection so that 10 mg/L chlorine is achieved immediately after mixing. The vol
Vlada [557]

<u>Answer:</u> The mass of chlorine needed by the plant per day is 9.4625\times 10^8mg

<u>Explanation:</u>

We are given:

Volume o water treated per day = 25,000,000 gallons

Converting this volume from gallons to liters, we use the conversion factor:

1 gallon = 3.785 L

So, \frac{3.785L}{1\text{ gallon}}\times 25,000,000\text{ gallons}=9.4625\times 10^7L

Amount of chlorine applied for disinfection = 10 mg/L

Applying unitary method:

For 1 L of water, the amount of chlorine applied is 10 mg

So, for 9.4625\times 10^7L of water, the amount of chlorine applied will be \frac{10mg}{1L\times 9.4625\times 10^7L}=9.4625\times 10^8mg

Hence, the mass of chlorine needed by the plant per day is 9.4625\times 10^8mg

6 0
3 years ago
Has 3 valence electrons and 4 energy levels ?
AVprozaik [17]

You are looking for an element in the fourth period and a transition metal. As most have about 3 valence electrons. Gallium and Scandium work perfectly.

8 0
3 years ago
Read 2 more answers
I WILL GIVE THE BRAINLIEST
lubasha [3.4K]

Ans 1. Both

Ans 2. Once inside plants, carbon moves through food chains, where organisms become nutrients including herbivores, carnivores and ultimately, decomposers. Once buried in the soil, carbon can be converted into fossil fuels over long periods of time and then also reenter the atmosphere by combustion. The Law of Conservation of Matter states that matter cannot be created or destroyed. The carbon cycle is an example of the Law

Ans 3. Most of the chemical energy needed for life is stored in organic compounds as bonds between carbon atoms and other atoms. The law of conservation of energy states that energy can not be created or destroyed. Thus, just like matter energy is also conserved in the process.

Hope it helps

3 0
4 years ago
How many moles of potassium are contained in 150 g of potassium
BaLLatris [955]

Answer:

150 g of potassium contained 3.8 moles of potassium.

Explanation:

Given data:

Mass of potassium = 150 g

Moles of potassium = ?

Solution:

Number of moles = mass/ molar mass

Molar mass of potassium = 39 g/mol

Now we will put the values in formula:

Number of moles = mass/ molar mass

Number of moles = 150 g/ 39 g/mol

Number of moles = 3.8 mol

150 g of potassium contained 3.8 moles of potassium.

3 0
4 years ago
A 2.300×10−2 m solution of nacl in water is at 20.0∘c. the sample was created by dissolving a sample of nacl in water and then b
lilavasa [31]

The given question is incomplete. The complete question is as follows.

A 2.300×10−2 m solution of nacl in water is at 20.0∘c. the sample was created by dissolving a sample of nacl in water and then bringing the volume up to 1.000 l. it was determined that the volume of water needed to do this was 999.4 ml . the density of water at 20.0∘c is 0.9982 g/ml.

Calculate the molality of the salt solution.

Express your answer to four significant figures and include the appropriate units.

Explanation:

Molality is defined as the number of moles present in kg of a solvent.

Mathematically,     Molality = \frac{\text{moles of solute}}{\text{mass of solvent}}

Also,

      Mole of solute = Molarity of solute x Volume of solution

                               = (0.0230 M) x (1.000 L) = 0.0230 mol of solute

Therefore, mass of solvent will be as follows.

     999.4 mL \times (\frac{0.9983 g}{1 mL})

                  = 997.7 g

                  = 0.9977 kg        (as 1 kg = 1000 g)

Therefore, we will calculate the molality as follows.

          Molality = \frac{0.0230 mol}{0.9977 kg}

                   = 0.02306 mol/kg

thus, we can conclude that molality of the given solution is 0.02306 mol/kg.

8 0
3 years ago
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