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3 years ago

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Some athletes have as little as 3.0% body fat. If such a person has body mass of 65 kg,how many pounds of body fat does tha

t person have?

1 answer:

coldgirl [10]3 years ago

8 0

They would have 5%:::::)

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The mass of the ocean is about 1.8 1021 kg. if the ocean contains 1.076% by mass sodium ions, na+, what is the mass in kilograms

castortr0y [4]

In chemistry, if you want to express the amount of a substance out of the total amount, you express it in concentration. There are numerous units of measurement: molarity, molality, normality, mass percentages, volume percentage, or a mix of both. For this problem, the unit used for concentration is in mass percentages. The formula would be

Percentage Concentration = [(Actual Amount of Substance)/(Total amount of all substances)] * 100

Since we are given with the total mass of all the substances in the ocean and the percentage concentration, the only missing information is the actual amount of Na+ in the ocean. Substituting the values:

1.076 = (Amount of Na+ /1.8×10²¹ kg)*100
Amount of Na+ = 1.9368×10¹⁹ kg

5 0

3 years ago

Explain how the following changes would affect the rate of the reaction of 2-bromo-3-methylbutane with methanol: Part A The alky

swat32

Answer:

The reaction will be slower because the leaving group will be poorer.

Explanation:

One Important thing to put at the back of our mind is that weak bases are good leaving groups. Another thing to take note is that in the halogen series(which is our main subject in this question) as you go down the group the greater or the more heavy the halide is and the heavier halides are more stable that is Bromine will be more stable than chlorine.

Now, we are now told that the bromo halide is been replaced by the chloro halide which means that the rate of Reaction will surely decrease because the leaving group. The cl^- is a stronger base.

6 0

3 years ago

Un tecnico di laboratorio deve preparare una soluzione di carbonato di sodio decaidrato, Na2CO3⋅ 10 H2O per eseguire alcune anal

fiasKO [112]

Answer:

1. 3.70 g Na₂CO₃·10H₂O

2. 50.0 mL of the first solution

Explanation:

1. Prepare the solution

(a) Calculate the molar mass of Na₂CO₃·10H₂O

$\begin{array}{rrr}\textbf{Atoms} &\textbf{M}_{\textbf{r}} & \textbf{Mass/u}\\\text{2Na} & 2\times22.99 & 45.98\\\text{1C} & 1\times 12.01 & 12.01\\\text{13O}&13 \times16.00 & 208.00\\\text{20H}&20 \times 1.008 & 20.16\\&\text{TOTAL =} & \mathbf{286.15}\\\end{array}$

The molar mass of Na₂CO₃·10H₂O is 286.15 g/mol.

(b) Calculate the moles of Na₂CO₃·10H₂O

$\text{Moles of Na$_{2}$CO$_{3}\cdot$10H$_{2}$O}\\= \text{0.250 L solution} \times \dfrac{\text{0.0500 mol Na$_{2}$CO$_{3}\cdot$10H$_{2}$O}}{\text{1 L solution}}\\\\= \text{0.0125 mol Na$_{2}$CO$_{3}\cdot$10H$_{2}$O}$

(c) Calculate the mass of Na₂CO₃·10H₂O

$\text{Mass of Na$_{2}$CO$_{3}\cdot$10H$_{2}$O }\\= \text{0.012 50 mol Na$_{2}$CO$_{3}\cdot$10H$_{2}$O } \times \dfrac{\text{296.15 g Na$_{2}$CO$_{3}\cdot$10H$_{2}$O}}{\text{1 mol Na$_{2}$CO$_{3}\cdot$10H$_{2}$O}}\\\\= \text{3.70 g Na$_{2}$CO$_{3}\cdot$10H$_{2}$O}\\\text{You need $\large \boxed{\textbf{3.70 g}}$ of Na$_{2}$CO$_{3}\cdot$10H$_{2}$O}$

2. Dilute the solution

We can use the dilution formula to calculate the volume needed.

V₁c₁ = V₂c₂

Data:

V₁ = ?; c₁ = 0.0500 mol·L⁻¹

V₂ = 100 mL; c₂ = 0.0250 mol·L⁻¹

Calculation:

$\begin{array}{rcl}V_{1}c_{1} & = & V_{2}c_{2}\\V_{1}\times \text{0.0500 mol/L} & = & \text{100 mL} \times\text{0.0250 mol/L}\\0.0500V_{1}& = & \text{2.500 mL}\\V_{1}&=& \dfrac{\text{2.500 mL}}{0.0500}\\\\& = & \text{50.0 mL}\\\end{array}\\\text{You need $\large \boxed{\textbf{50.0 mL}}$ of the concentrated solution.}$

7 0

3 years ago

Helpppppppppppppp!!!!!!!

OlgaM077 [116]

Something on a man i think it’s crocs

3 0

3 years ago

What is the mass of helium atom whose atomic weight is 4.003 g/mol?

tino4ka555 [31]

Answer:

Atoms He (Avogadro’s number) → Moles of He (molar mass of He) → Mass of He

• molar mass of He (from the periodic table) = 4.003 g/mol

• Avogadro’s Number: Avogadro’s number gives us the number of entities present in 1 mole: 6.022 × 1023 He atoms in 1 mole of He

hope this is help full please mark me Brainliest

4 0

3 years ago