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MatroZZZ [7]
3 years ago
5

Calcium levels in people are normally distributed with a mean of 9.5 mg/dL and a standard deviation of 0.3 mg/dL. Individuals wi

th calcium levels in the bottom 10% of the population are considered to have low calcium levels. Find the calcium level that is the borderline between low calcium levels and those not considered low. Carry your intermediate computations to at least four decimal places. Round your answer to one decimal place.
Chemistry
1 answer:
34kurt3 years ago
6 0

Answer:

9.1 mg/dL

Explanation:

A normal distribution is symmetrical, the area below the curve of negative Z-scores is equal to the area below the curve of positive Z-scores, Z measures the statistic observed and the parameter of the population.

And it is:

Z = (x - μ)/σ

where μ is the mean (9.5 mg/dL), x is the borderline, and σ is the standard deviation, which is 0.3 mg/dL.

The Z-score can be calculated in excel by the function =NORMSINV, and the factor will be the percente considered (10% = 0.1)

NORMSINV(0.1) = -1.28155

So,

-1.28155 = (x - 9.5)/0.3

x - 9.5 = -0.384465

x = 9.1 mg/dL

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The addition of hydrochloric acid to a silver nitrate solution precipitates silver chloride according to the reaction:
Nimfa-mama [501]

Answer:

Enthalpy change for the reaction is -67716 J/mol.

Explanation:

Number of moles of AgNO_{3} in 50.0 mL of 0.100 M of AgNO_{3}

= Number of moles of HCl in 50.0 mL of 0.100 M of HCl

= \frac{0.100}{1000}\times 50.0 moles

= 0.00500 moles

According to balanced equation, 1 mol of AgNO_{3} reacts with 1 mol of HCl to form 1 mol of AgCl.

So, 0.00500 moles of AgNO_{3} react with 0.00500 moles of HCl to form 0.00500 moles of AgCl

Total volume of solution = (50.0+50.0) mL = 100.0 mL

So, mass of solution = (100.0\times 1.00) g = 100 g

Enthalpy change for the reaction = -(heat released during reaction)/(number of moles of AgCl formed)

= \frac{-m_{solution}\times C_{solution}\times \Delta T_{solution}}{0.00500mol}

= \frac{-100g\times 4.18\frac{J}{g.^{0}\textrm{C}}\times [24.21-23.40]^{0}\textrm{C}}{0.00500mol}

= -67716 J/mol

[m = mass, c = specific heat capacity, \Delta T = change in temperature and negative sign is included as it is an exothermic reaction]

4 0
3 years ago
Convert mass to moles for both reactants. (round to 2 significant figures.)
Maslowich

Answer:

Explanation:

Given parameters:

Mass of CuCl₂  = 2.50g

Mass of Al  = 0.50g

Unknown:

Number of moles of CuCl₂ and Al  = ?

Solution:

To solve this problem, we must understand that the number of moles is a fundamental property used in stoichiometry calculations.

         Number of moles  = \frac{mass}{molar mass}

Molar mass of CuCl₂  = 63.6 + 2(35.5) = 134.5g/mole

Molar mass of Al  = 26.98g/mole

          Number of moles of  CuCl₂  = \frac{2.5}{134.5}  = 0.019moles

        Number of moles of Al  = \frac{0.5}{26.98}   = 0.019moles

4 0
3 years ago
Read 2 more answers
During region C of the graph above the energy being absorbed is a. increasing the velocity of the water particles. b. increasing
Mkey [24]

Answer:

Your answer would be B. Increasing the distance between the water molecules and increasing their phase energy.

Explanation:

Hope this helps you answer this question!

7 0
2 years ago
Help me plz, I need help on this.
kirza4 [7]
Omg i lost everything ugh
To do it again

1. 12g+2(16g)= 44g/mol
25.01/ 44g/mol= .... mol

2. 14g+3(1g)= 17g/mol
34.05g/ 17g/mol=.... mol

3. 23g+1g+ 12g+ 3(16g)= 84g/mol
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4. 6(12g)+12(1g)+6(16g)= 180g/mol
123.44g/ 180g/mol=.... mol

5. 23g+16g+1g= 40g/mol
2.2mol x 40g/mol= .... g

6. 2(35g)= 71g/mol
4.5mol x 71g/mol= .... g

7. 137g+ 2(14g)+ 6(16g)= 261g/mol
0.002mol x 261g/mol= ....g

8. 2(56g)+ 3(32g)+ 12(16g)= 400g/mol
5.4mol x 400g/mol=.... g

I cant believe i had to do this all over

4 0
3 years ago
Explain how you can convert from the number of representative particles of a substance to moles of that substance.
Scrat [10]

Answer:

  • the number of representative contain in 1 mol of a substance equals to 6.o2x10^23 particles.
8 0
2 years ago
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