7.

True or false The atomic number of an element is always more than the mass number of that element.

Veseljchak [2.6K]

The sentence is true

8 0

3 years ago

QUICKEST GETS BRAINLIEST AND 7 POINTS

Angelina_Jolie [31]

Hello there.

Thomson's atomic model is best described by which of the following statements?

A nucleus with electrons moving around it like planets.

3 0

4 years ago

How fast must a 56.5-g tennis ball travel in order to have a de Broglie wavelength that is equal to that of a photon of green li

nikklg [1K]

Answer:vv

$v=2.17\times 10^{-26}\ m/s$

Explanation:

The expression for the deBroglie wavelength is:

$\lambda=\frac {h}{m\times v}$

Where,

$\lambda$ is the deBroglie wavelength

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

m is the mass of = $56.5\ g=0.0565\ kg$

v is the speed.

Wavelength = 5400 Å = $5400\times 10^{-10}\ m$

Applying in the equation as:-

$5400\times 10^{-10}=\frac{6.626\times 10^{-34}}{0.0565\times v}$

$v=\frac{331300000}{10^{34}\times \:1.5255}\ m/s$

$v=2.17\times 10^{-26}\ m/s$

7 0

4 years ago

3. During an experiment where 50.0 mL of a 1.0 M acid solution was mixed with 50.0 mL of a 1.0 M base solution, the temperature

Aleksandr-060686 [28]

Answer:

$\large \boxed{\text{-61 kJ$\cdot$mol$^{-1}$}}$

Explanation:

Data:

H₃O⁺ + OH⁻ ⟶ 2H₂O

V/mL: 50.0 50.0

c/mol·L⁻¹: 1.0 1.0

ΔT = 6.5 °C

ρ = 1.210 g/mL

C = 4.18 J·°C⁻¹g⁻¹

C_cal = 12.0 J·°C⁻¹

Calculations:

(a) Moles of acid

$\text{Moles of acid} = \text{0.0500 L} \times \dfrac{\text{1.0 mol}}{\text{1 L}} = \text{0.0500 mol}\\\\\text{Moles of base} = \text{0.0500 L} \times \dfrac{\text{1.0 mol}}{\text{1 L}} = \text{0.0500 mol}$

(b) Volume of solution

V = 50.0 mL + 50.0 mL = 100.0 mL

(c) Mass of solution

$\text{Mass of solution} = \text{100.0 mL} \times \dfrac{\text{1.10 g}}{\text{1 mL}} = \text{110.0 g}$

(d) Calorimetry

There are three energy flows in this reaction.

q₁ = heat from reaction

q₂ = heat to warm the water

q₃ = heat to warm the calorimeter

q₁ + q₂ + q₃ = 0

nΔH + mCΔT + C_calΔT = 0

0.0500ΔH + 1.10×4.18×6.5 + 12.0×6.5 = 0

0.0500ΔH + 2989 + 78.0 = 0

0.0500ΔH + 3067 = 0

0.0500ΔH = -3067

ΔH = -3067/0.0500

= -61 000 J/mol

= -61 kJ/mol

$\text{The enthalpy of reaction is $\large \boxed{\textbf{-61 kJ$\cdot$mol$^{\mathbf{-1}}$}}$}$

Note: The answer can have only two significant figures because that is all you gave for the change in temperature.

7 0

3 years ago

Identify the acids and the bases in the chemical equation.

DiKsa [7]

Answer:

Acids: $HCl, C_5H_5NH^+$

Bases: $C_5H_5N, Cl^-$

Explanation:

According to the Bronsted-Lowry acid-base theory, an acid is a proton donor and a base is a proton acceptor. In this case, notice that $HCl$ donates a proton, since after it loses a proton, it becomes a chloride anion. Therefore, $HCl$ is a Bronsted acid.

Similarly, $C_5H_5N$ is a proton acceptor and, therefore, a Bronsted base, since it becomes $C_5H_5NH^+$ .

If we look at the reverse reaction, chloride can gain a proton to become $HCl$ , meaning it's a conjugate base.

Finally, $C_5H_5NH^+$ is a conjugate acid, since it can donate a proton to chloride.

7 0

3 years ago