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alexandr1967 [171]
1 year ago
10

How many mL of a 4.50M NaBr solution are needed to make 250 mL of a 0.75M solution of NaBr?

Chemistry
1 answer:
sweet [91]1 year ago
8 0
M1V1=M2V2

(4.50)(x)=(0.75)(250)
(4.50)(x)=187.5
x=41.67 mL
You might want to double check the formula used, but as a chem student I’m confident this is right
You might be interested in
Beaker A contains 2.06 mol of copper ,and Barker B contains 222 grams of silver.Which beaker the larger number of atom?
Dmitry [639]

Answer:

The number of copper atoms 12.405 ×10²³ atoms.  

The number of silver atoms  13.13 ×10²³ atoms.

Beaker B have large number of atoms.

Explanation:

Given data:

In beaker A

Number of moles of copper = 2.06 mol

Number of atoms of copper = ?

In beaker B

Mass of silver = 222 g

Number of atoms of silver = ?

Solution:

For beaker A.

we will solve this problem by using Avogadro number.

The number 6.022×10²³ is called Avogadro number and it is the number of atoms in one mole of substance.

While we have to find the copper atoms in 2.06 moles.

So,

63.546 g = 1 mole = 6.022×10²³ atoms

For 2.06 moles.

2.06 × 6.022×10²³ atoms

The number of copper atoms 12.405 ×10²³ atoms.  

For beaker B:

107.87 g = 1 mole = 6.022×10²³ atoms

For 222 g

222 g / 101.87 g/mol = 2.18 moles

2.18 mol × 6.022×10²³ atoms = 13.13 ×10²³ atoms

8 0
2 years ago
In the manufacture of paper, logs are cut into small chips, which are stirred into an alkaline solution that dissolves several o
Kitty [74]

Answer:

The estimated feed rate of logs is 14.3 logs/min.

Explanation:

The product of the process is 2000 tons/day of dry wood pulp, of 85 wt% of cellulose. That represents (2000*0.85)=1700 tons/day of cellulose.

That cellulose has to be feed by the wood chips, which had 47 wt% of cellulose in its composition. That means you need (1700/0.47)=3617 tons/day of wood chips to provide all that cellulose.

Th entering flow is wood chips with 45 wt% of water. This solution has an specific gravity of 0.640.

To know the specific gravity of the wood chips we have to write a volume balance. We also know that Mw=0.45*M and Mc=0.55*M.

V=V_c+V_w\\\\M/\rho=M_c/\rho_c+Mw/\rho_w\\\\M/\rho=0.55*M/\rho_c+0.45*M/\rho_w\\\\1/\rho=0.55/\rho_c +0.45/\rho_w\\\\0.55/\rho_c=1/\rho-0.45/\rho_w\\\\0.55/\rho_c=1/(0.64*\rho_w)-0.45/\rho_w=(1/\rho_w)*(\frac{1}{0.64}-\frac{0.45}{1}  )\\\\0.55/\rho_c=1.1125/\rho_w\\\\\rho_c=\frac{0.55}{1.1125}*\rho_w= 0.494*\rho_w

The specific gravity of the wood chips is 0.494.

The average volume of a log is

V_l=(\pi*D^{2} /4)*L=(3.1416*\frac{8^{2}  \, in^{2} }{4} )*9ft*(\frac{12 in}{1ft})= 21714 in^{3}=12.57 ft^{3}

The weight of one log is

M=\rho*V=0.494*\rho_w*12.57  ft^{3}\\\\M=0.494*62.4\frac{lbm}{ft^{3} }*12.57ft^{3}\\\\M=387.5lbm

To provide 3617 ton/day of wood chips, we need

n=\frac{supply}{M_{log}}=\frac{3617 tons/day}{387.5 lbm}*\frac{2204lbm}{1ton}\\\\n=20573 logs/day=14.3 logs/min

The feed rate of logs is 14.3 logs/min.

7 0
2 years ago
Read 2 more answers
A vitamin c tablet containing 250 mg of ascorbic acid (c6h8o6; ka=8.0×10−5) is dissolved in a 250 ml glass of water. what is the
ikadub [295]
First, we have to get the initial [C6H8O6] = mass/molar mass
 
when the molar mass of C6H8O6 = 176.12 g/mol

∴[C6H8O6] = 0.25 g / 176.12 g/mol 
                    = 0.00142 M

when 
               C6H8O6 ⇄  H+   +  C6H7O6-
intial       0.00142 M       0           0
change    -X                   +X          +X
Equ       (0.00142-X)         X            X
 

so, Ka = [H+][C6H7O6-] / [C6H8O6]

by substitution:

8 x 10^-5 = X * X / (0.00142-X) by solving this equation for X

∴ X = 0.000299 
∴[H+] = 0.000299

∴PH = -㏒[H+]
     
        = -㏒ 0.000299
        = 3.52
6 0
1 year ago
A Gas OCCUPIES 525ML AT A PRESSURE OF 85.0 kPa WHAT WOULD THE VOLUME OF THE GAS BE AT THE PRESSURE OF 65.0 kPa
german

Boyle's law of ideal gas: This law states that the volume of a gas is inversely proportional to its pressure at a constant temperature. Acc to this law we can write the relation of pressure and volume as:

PV=Constant

That means:

P_{1}V_{1}=P_{2}V_{2}

From that equation we can calculate Volume of gas at a certain pressure:

P₁=Initial pressure

V₁=Initial volume

P₂=Final pressure

V₂= Final volume

Here P₁, initial pressure is given as 85.0 kPa

V₁, initial volume is given as 525 mL

P₂, final pressure is 65.0 kPa

P_{1}V_{1}=P_{2}V_{2}

so,

V_{2}=85\times 525\div 65

=686 mL

Volume of gas will be 686 mL.

8 0
2 years ago
Read 2 more answers
The diagram below shows the different phase transitions that occur in matter. Which arrow represents the transition in which dew
oksian1 [2.3K]

Answer:

  • <u>The arrow labeled 4: from gas to liquid.</u>

Explanation:

<em>Dew</em> is a manifestation of water condensation.

The air that surrounds us contains water vapor (humidity) from the evaporatoin of the water in the rivers, lakes, and the water with which you water the plants of your garden.

During the night, and specially in the early morning, before dawn, the temperature of the air descends, and part of the vapor in the air condensates in tiny droplets that accumulate over the surface of the plant's leaves, and other solid surfaces like the winshields and hoods of the cars.

Then, the phase transition that occurs is from gas (vapor) to liquid, which is called condensation and represented with the arrow labeled 4 on the diagram.

3 0
1 year ago
Read 2 more answers
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