Chemical energy is released when molecular bonds are formed. True False

Which planet is sometimes called Uranus’s twin? Saturn Pluto Jupiter Neptune

sattari [20]

Neptune.

Because the size, mass, composition and rotation of Neptune and Uranus are very similar they're sometimes refered to as planetary twins.

7 0

3 years ago

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_____ might be able to detect tumors based on its use of X-rays and ability to produce cross-sectional images of the brain.

MatroZZZ [7]

Answer: CAT (computerized axial tomography) scan

Explanation:

Computerized Axial Tomography (CAT) scan is an X-ray examination in which a computer generates images showing cross-section views of a patient's internal parts (brain, blood vessels and etc.)

CAT scan can identify normality and detect abnormalities (such as tumor and degenerated cells) in the internal organs and structures and hence, this information are used to guide other medical processes.

6 0

3 years ago

Which of the "planetary health measures" shown here have humans already exceeded?

ella [17]

Answer:

the answer is atmospheric carbon dioxide

Explanation:

4 0

2 years ago

Consider the reaction:

stich3 [128]

Answer:

$\large \boxed{\text{-851.4 kJ/mol}}$

Explanation:

2Al(s) + Fe₂O₃(s) ⟶ Al₂O₃(s) + 2Fe(s); ΔᵣH = ?

The formula for calculating the enthalpy change of a reaction by using the enthalpies of formation of reactants and products is

$\Delta_{\text{r}}H^{\circ} = \sum \Delta_{\text{f}} H^{\circ} (\text{products}) - \sum\Delta_{\text{f}}H^{\circ} (\text{reactants})$

2Al(s) + Fe₂O₃(s) ⟶ Al₂O₃(s) + 2Fe(s)

ΔfH°/kJ·mol⁻¹: 0 -824.3 -1675.7 0

$\begin{array}{rcl}\Delta_{\text{r}}H^{\circ} & = & [1(-1675.7) + 2(0)] - [2(0) - 1(-824.3)]\\& = & -1675.7 + 824.3\\& = & \textbf{-851.4 kJ/mol}\\\end{array}\\\text{The enthalpy change is } \large \boxed{\textbf{-851.4 kJ/mol}}$

7 0

4 years ago

4. Your mission, if you choose to accept it, is to make 10mmol/L acetate buffer, pH5.0. Beginning with 10mmol/L HAc, what concen

julia-pushkina [17]

Answer:

6,45mmol/L of NaOH you need to add to reach this pH.

Explanation:

CH₃COOH ⇄ CH₃COO⁻ + H⁺ pka = 4,74

Henderson-Hasselbalch equation for acetate buffer is:

5,0 = 4,74 + log₁₀ $\frac{[CH_{3}COO^-]}{[CH_{3}COOH]}$

Solving:

1,82 = $\frac{[CH_{3}COO^-]}{[CH_{3}COOH]}$ (1)

As total concentration of acetate buffer is:

10 mM = [CH₃COOH] + [CH₃COO⁻] (2)

Replacing (2) in (1)

[CH₃COOH] = 3,55 mM

And

[CH₃COO⁻] = 6,45 mM

Knowing that:

CH₃COOH + NaOH → CH₃COO⁻ + Na⁺ + H₂O

Having in the first 10mmol/L of CH₃COOH, you need to add 6,45 mmol/L of NaOH. to obtain in the last 6,45mmol/L of CH₃COO⁻ and 3,55mmol/L of CH₃COOH .

I hope it helps!

7 0

3 years ago