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3 years ago

44.90 g of reactants are placed in a beaker

Chemistry

1 answer:

sergiy2304 [10]3 years ago

7 0

Answer:

D. -1882J

Explanation:

We can solve the energy released in a chemical reaction in an aqueous medium using the equation:

Q = -m*C*ΔT

Where Q is energy (In J),

m is mass of water (45.00g)

C is specific heat of water (4.184J/g°C)

And ΔT is change in temperature (25.00°C - 15.00°C = 10.00°C)

Replacing:

Q = -45.00*4.184J/g°C*10.00°C

Q = -1882J

Right answer is:

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Describe the ways you can know that a chemical reaction has occurred.

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Signs that a chemical reaction is occurring are: 1. change in color 2. change in odor 3. change in pH, as in changes from acid to base or base to acid

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4 years ago

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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

Answer: The mass of sodium acetate that must be added is 30.23 grams

Explanation:

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

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3 years ago

The properties of a substance are not affected by chemical reactions. O True O False

ElenaW [278]

Answer:

False

Explanation:

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3 years ago

14. An increase in temperature results in an increase in ...

shusha [124]

Answer: its C. and B.

Explanation:

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3 years ago

Which of the following has the most atoms per mole?

BabaBlast [244]

Answer:

e) Na₃PO₄

Explanation:

a) BaSO₄

1 mole of BaSO ₄ = 6.022×10²³ molecules

1 mole of BaSO ₄ contain 1 atom of Ba one atom of S and four atoms of O.

Total number of atoms = 6 atoms

6.022×10²³ × 6 atoms = 36.132 ×10²³ atoms

b) NaNO₂

1 mole of NaNO₂= 6.022×10²³ molecules

1 mole of NaNO₂ contain 1 atom of Na one atom of N and two atoms of O.

Total number of atoms = 4 atoms

6.022×10²³ × 4 atoms = 24.088 ×10²³ atoms

c)KMnO₄

1 mole of KMnO₄ = 6.022×10²³ molecules

1 mole of KMnO₄ contain 1 atom of K one atom of Mn and four atoms of O.

Total number of atoms = 6 atoms

6.022×10²³ × 6 atoms = 36.132 ×10²³ atoms

d) KCl

1 mole of KCl = 6.022×10²³ molecules

1 mole of KCl contain 1 atom of K one atom of Cl.

Total number of atoms = 2 atoms

6.022×10²³ × 2 atoms = 12.044 ×10²³ atoms

e) Na₃PO₄

1 mole of Na₃PO₄ = 6.022×10²³ molecules

1 mole of Na₃PO₄ contain 3 atom of Na one atom of P and four atoms of O.

Total number of atoms = 8 atoms

6.022×10²³ × 8 atoms = 48.176×10²³ atoms

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3 years ago