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konstantin123 [22]
4 years ago
5

What is the human body's first line of defense against invading pathogens such as bacteria and viruses?

Chemistry
1 answer:
Sedbober [7]4 years ago
3 0
ANTI---------- BODIES!!!!!!!
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Which describes an covalent bond?
Ilya [14]

Answer:

is there choices you have to pick from

Explanation:

or do you have to describe a covalent bond ?

8 0
3 years ago
Read 2 more answers
The molarity of an aqueous sodium phosphate solution is 0.650 M. What is the molality of sodium ions present in this solution? T
netineya [11]

Answer:

molality of sodium ions is 1.473 m

Explanation:

Molarity is moles of solute per litre of solution

Molality is moles of solute per kg of solvent.

The volume of solution = 1 L

The mass of solution = volume X density = 1000mL X 1.43 = 1430 grams

The mass of solute = moles X molar mass of sodium phosphate = 0.65X164

mass of solute = 106.6 grams

the mass of solvent = 1430 - 106.6 = 1323.4 grams = 1.3234 Kg

the molality = \frac{moles of solute}{mass of solvent in kg}=\frac{0.65}{1.323}= 0.491m

Thus molality of sodium phosphate is 0.491 m

Each sodium phosphate of molecule will give three sodium ions.

Thus molality of sodium ions = 3 X 0.491 = 1.473 m

7 0
3 years ago
Which of the following compounds are held together by ionic bonds? Select all that apply.
Sergeu [11.5K]

Answer:

Explanation:

All of above except carbon dioxide

7 0
3 years ago
The enthalpy of vaporization of Bromine is 15.4 kJ/mol. What is the energy change when 80.2 g of Br2 condenses to a liquid at 59
Aleksandr-060686 [28]

The enthalpy of vaporization of Bromine is 15.4 kJ/mol. -7.7 kJ is the energy change when 80.2 g of Br₂ condenses to a liquid at 59.5°C.

<h3>What is Enthalpy of Vaporization ?</h3>

The amount of enthalpy or energy that must be added to a liquid substance into gas substance is called Enthalpy of Vaporization. It is also known as Latent heat of vaporization.

<h3>How to find the energy change from enthalpy of vaporization ?</h3>

To calculate the energy use this expression:

Q = n \Delta H_{\text{vapo.}

where,

Q = Energy change

n = number of moles

\Delta H_{\text{Vapo.}} = Molar enthalpy of vaporization

Now find the number of moles

Number of moles (n) = \frac{\text{Given Mass}}{\text{Molar mass}}

                                   = \frac{80.2\ g }{159.8\ g/mol}

                                   = 0.5 mol

Now put the values in above formula we get

Q = - n \Delta H_{\text{vapo.}         [Negative sign is used because Br₂ condensed here]

   = - (0.5 mol × 15.4 kJ/mol)

   = - 7.7 kJ

Thus from the above conclusion we can say that The enthalpy of vaporization of Bromine is 15.4 kJ/mol. -7.7 kJ is the energy change when 80.2 g of Br₂ condenses to a liquid at 59.5°C.

Learn more about the Enthalpy of Vaporization here: brainly.com/question/13776849

#SPJ1

8 0
2 years ago
What will be the final temperature of the solution in a coffee cup calorimeter if a 50.00 mL sample of 0.250 M HCl(aq) is added
padilas [110]

Answer:

21.21°C will be the final temperature of the solution in a coffee cup calorimeter.

Explanation:

HCl+NaOH\rightarrow H_2O+NaCl

\Delta H = enthalpy change = -57.2 kJ/mol of NaOH

Moles of sodium hydroxide = n

Molarity of the NaOH = 0.250 M

Volume of NaOH solution = V = 50.00 mL = 0.050 L

n=Molarity\times V=0.250 M\times 0.050 L= 0.0125 mol

Moles of HCl = n'

Molarity of the HCl= 0.250 M

Volume of HCl solution = V' = 50.00 mL = 0.050 L

n'=Molarity\times V=0.250 M\times 0.050 L= 0.0125 mol

Since 1 mole of Hcl reacts with 1 mole of NaoH. Then 0.0125 mole of HCl will react with 0.0125 mole of NaOH.

The enthalpy change during the reaction.

\Delta H=-\frac{q}{n}

q=\Delta H\times n=-57.2 kJ/mol \times 0.0125 mol= -0.715 kJ=-715 J

q = heat released on reaction= -715 J

now, we calculate the heat gained by the solution.:

Q= -q = -(-715 J) = 715 J

m = mass of the solution = ?

Volume of the solution formed by mixing, v = 50.00 ml + 50.00 mL = 100.00 mL

Density of the solution = density of water = d = 1 g/mL

mass=density\times volume=d\times v=1 g/ml \times 100.00 ml=100 g

m = 100 g

q = heat gained = ?

c = specific heat = 4.18 J/^oC

T_{f} = final temperature = ?

T_{i} = initial temperature = 19.50^oC

Q=mc\times (T_{f}-T_{i})

Now put all the given values in the above formula, we get:

715 J=100 g\times 4.18J/^oC\times (T_f-19.50)^oC

T_f=21.21 ^oC

21.21°C will be the final temperature of the solution in a coffee cup calorimeter.

5 0
3 years ago
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