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3 years ago

Brianliest for whoever gets this right with step by step method

1 answer:

8 0

The Mr is the mass numbers of each element added up so…. Fe = 56, O=16, H=1 … now add these up with the number of each element -> there’s 1 Fe, and 3 Os and 3 Hs as they are in brackets with a 3 outside-> (56+16+16+16+1+1+1=107) … your answer is 107

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A hydrogen atom requires a minimum energy of 2.18×10^-18 J atom to remove an electron from its ground state level. Determine whe

frosja888 [35]

Just find the energy of the blueviolet light with a wavelength of 434.0 nm using the formula:

E = hc / lambda

E = energy
c= speed of light = 3 x 10^8 m/s
h = planck's constant = 6.6 x 10^{-34} m^2 kg / s
lambda = 434 nm = 434 x 10^{-9} m

Putting these values (with appropriate units) in the above formula :

we get: Energy, E = 4.5 x 10^{-19} J

E = 0.45 x 10^{-18} J

Now, the minimum energy is 2.18×10^-{18} J but our energy is 0.45 x 10^{-18} J which is less.
Means the electron will not be removed

5 0

3 years ago

Which of the following correctly describes voltage difference?

7nadin3 [17]

Voltage difference is the push that causes charges to flow from high to low areas.

7 0

3 years ago

Which of the example most complete description an objects motion?

Rashid [163]

c] The golfer sent the golf ball flying toward the cup to score a hole in one.

4 0

3 years ago

Sodium metal reacts with water to produce hydrogen gas and sodium hydroxide according to the chemical equation shown below.

UNO [17]

Answer: The enthalpy change of the reaction is -361.6 kJ

Explanation:

To calculate the number of moles, we use the equation:

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

Moles of sodium = 0.025 moles

Molar mass of sodium = 23 g/mol

Putting values in above equation, we get:

$0.025mol=\frac{\text{Mass of sodium}}{23g/mol}\\\\\text{Mass of sodium}=(0.025mol\times 23g/mol)=0.575g$

We are given:

Mass of water = 100.00 g

Mass of sodium = 0.575 g

Mass of solution = 100.00 + 0.575 = 100.575 g

To calculate the amount of heat absorbed, we use the equation:

$q=m\times C\times \Delta T$

where,

q = amount of heat absorbed = ?

m = mass of solution = 100.575 g

C = specific heat capacity of solution = 4.18 J/g°C

$\Delta T$ = change in temperature = $(T_2-T_1)=(35.75-25.00)=10.75^oC$

Putting all the values in above equation, we get:

$q=100.575g\times 4.18J/g^oC\times 10.75^oC=4519.34J=4.52kJ$

When heat is absorbed by the solution, this means that heat is getting released by the reaction.

Sign convention of heat:

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

For the given chemical reaction:

$2Na(s)+2H_2O(l)\rightarrow NaOH(aq.)+H_2(g)$

When 0.025 moles of sodium is reacted, the heat released by the reaction is 4.52 kJ

So, when 2 moles of sodium will react, the heat released by the reaction will be = $\frac{4.52}{0.025}\times 2=361.6kJ$

Hence, the enthalpy change of the reaction is -361.6 kJ

6 0

3 years ago

Which of the following is not a property of a buffer solution? a) It is a mixture of a weak acid and its conjugate base. b) Resi

m_a_m_a [10]

Answer:

e) pH is independent of concentration.

Explanation:

a) It is a mixture of a weak acid and its conjugate base. TRUE. A buffer is defined as a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid.

b) Resists pH changes because it reacts with added acid or base. TRUE. Thermodynamically, the reaction of added acid or base is faster with the buffer mixture than with H⁺ or OH⁻ ions of the solutions.

c) The maximum buffer capacity is at pH = pKa. TRUE. The buffer capacity is pka±1. For this, buffer capacity is maximum in pka.

d) pH is dependent on the solution ionic strength and temperature. TRUE. Ionic strength and temperature are factors that influence concentrations of ions in solutions as the H⁺ ion that is the responsible

e) pH is independent of concentration. FALSE. pH in a buffer depends completely of concentrations of the acid and its conjugate base or vice versa.

I hope it helps!

8 0

3 years ago