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3 years ago

What are the main functions of the human skeletal system?

Chemistry

2 answers:

Basile [38]3 years ago

7 0

Answer:

It´s letter A

Explanation:

laiz [17]3 years ago

3 0

Answer:

The answer is A.........

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when copper is bombarded with high energy electron x rays are emitted.Calculate the energy(in joule) associated with photons if

kakasveta [241]

The answer that i got was three
i redid it and got some answer like 4.62 x1014<span> Hz</span>

3 0

3 years ago

Suppose an ice cube weighing 36.0 g at a temperature of 10°C is placed in 360 g water at a temperature of 20°C. Calculate the te

Scilla [17]

Answer:

10.44 °C

Explanation:

When the thermal equilibrium is reached, both of the substances have the same final temperature (T). The liquid water will lose heat, and the ice cube will absorb this heat. The temperature of the ice will increase until it reaches 0°C, at this temperature, it will change of phase for liquid, absorbing heat, but without a change in the temperature. Then the temperature will increase until the equilibrium.

By the energy conservation, the total amount of heat must be equal to 0:

Qice + Qmelting + Qliquid1 + Qliquid2 = 0

Liquid 1 is the ice after melting, and liquid 2 the liquid that was already at the flask. When there's a change of temperature:

Q = n*c*ΔT, where n is the number of moles, c is the heat capacity and ΔT is the temperature change (final - initial). The temperature variation in °C is equal in K, so the temperature may be used in °C.

The melting heat is:

Q = n*Hfus, Hfus = 6007 J/mol

The molar mass of the water is 18 g/mol, so the number of moles of the water and the ice are:

nwater = nliquid1 = 360/18 = 20 moles

nice = 36/18 = 2 moles

Qice + Qmelting + Qliquid1 + Qliquid2 = 0

2*38*(0 - (-10)) + 2*6007 + 2*75*(T - 0) + 20*75*(T - 20) = 0

760 + 12014 + 150T + 1500T - 30000 = 0

1650T = 17226

T = 10.44 °C

4 0

3 years ago

An acid with the general formula RCOOH is used to make a 0.10 M solution in water. The pH of this acid solution is measured as 3

Sati [7]

Answer:

0.159 \%

Explanation:

The acid will dissociate according to the reaction shown below:-

$RCOOH + H_2O\rightleftharpoons RCOO^- + H_3O^+$

Given that, pH=3.8

The concentration of can be determined from the expression fo pH as:-

pH = - log $[H^+]$

3.8 = - log $[H^+]$

$[H^+]$ = $1.59\times 10^{-4}\ M$

The initial concentration of RCOOH was 0.10 M, then the percent dissociation was- calculated as shown below:-

$\% \ dissociation=\frac{1.59\times 10^{-4}}{0.10}\times 100=0.159\ \%$

3 0

2 years ago

6. dissolving ice tea mix in water

Cloud [144]

Answer:

Dissolving ice tea mix in water is a chemical change

Explanation:

It is a chemical change because you can not bring back the ice tea mix back if you mix it in water.

Hope it helps

6 0

3 years ago

A sample compound with a molar mass of 34.00g/mol is found to consist of 0.44g H and 6.92g O. Calculate both empirical and molec

balu736 [363]

Answer:

E.F= OH

M.F= $O_{2} H_{2}$

Explanation:

Empirical Formula

Step 1: Calculate mols of each element

0.44gH(1 mol H/ 1.008g H)= 0.4365 mol H

*note leave extra sig figs for calculations

6.92gO(1 mol O/ 16 g O)=0.4325 mol O

Step 2: Identify which is the smallest mol

*in this case 0.4365 mol H> 0.4325 mol O so we will use 0.4325 mol O

Step 3: Divide above calculations by the smallest mol

0.4325 mol O/0.4325= 1

0.4365 mol H/0.4325= 1.009 *rounds to 1

Step 4: use calculations as subscripts

Oxygen = 1 so the subscript will 1 (O)

Hydrogen = 1 so the subscript will 1 (H)

making E.F= OH

Molecular Formula:

Step 1: identify molecular mass and mass from the E.F

the molecular mass is given 34.00g/mol

the mass of the E.F is

(oxygen mass from periodic table)+(hydrogen mass from periodic table)

16+1.008= 17.008

Step 2:Divide the molecular mass by the mass given by the emipirical formula.

$\frac{34.00}{17.008}= 1.999$ round to 2

Step 3:Multiply the empirical formula (the subscripts) by this number to get the molecular formula. ANSWER: M.F=2(OH)- $O_{2} H_{2}$

3 0

3 years ago