Does mint really cool your breath? doing a science fair and also is there three good questions i could use for the topic?

True of false an unbalanced force cannot change the direction in which an object is moving

Andrei [34K]

False. An unbalanced force can change the direction in which an object is moving.

4 0

4 years ago

What is the indepent variable

Gwar [14]

It is a variable that does not count on others help.

7 0

3 years ago

What temperature will the water reach when 10.1 g CaO is dropped into a coffee cup containing 157 g H2O at 18.0°C if the followi

Zepler [3.9K]

Answer:

Final temperature attained by water = 34.6°C

Explanation:

The reaction of CaO and H₂O is an exothermic reaction. The equation of reaction is given below:

CaO + H₂O ----> Ca(OH)₂

The quantity of heat given off, ΔH°rxn = 64.8KJ/mol = 64800J/mol

Number of moles of CaO = mass/molar mass, where molar mass of Ca0 = 56g/mol, mass of CaO = 10.1g

Number of moles of CaO = 10.1g/56g/mol =0.179moles

Quantity of heat given off by 0.179 moles = 64800 *0.179 = 11599.2J/mol

Using the formula, Quantity of heat, q = mass * specific heat capacity * temperature rise.

mass of mixture = (10.1 + 157)g = 167.1g, Initial temperature = 18.0°C

Final temperature(T₂) - Initial temperature(T₁) = Temperature rise

11599.2J/mol = 167.1g * 4.18J/g·°C * ( T₂ - 18.0°C)

11599.2 = 698.478T₂ - 12572.604

11599.2 + 12572.604 = 698.478T₂

698.478T₂ = 24171.804

T₂ = 34.6°C

Therefore, final temperature attained by water = 34.6°C

6 0

3 years ago

Please answer these!!!

olasank [31]

Answer:

1.b. 2.5 mol

2.c.82.8%

3.d. synthesis

4.c . 2:2

5.d. 5 moles

6.c.5.02

7.d.3:1

8.d.2.68 moles

Explanation:

1.

$2RbNO_{3}\rightarrow 2RbNO_{2}+1O_{2}$

Here , 2 mole of RbNO3 will produce, 1 mole of O2

1 mole of RbNO3 will produce =

$\frac{1}{2}$ mole of O2

5 mole of RbNO3 will produce =

$\frac{1}{2}\times 5$

= 2.5 mole of O2

2 .

Molar mass of HCl = 1 + 35.45 = 36.45 gram

Molar mass of CO2 = 12 +32 = 44 gram

1 mole of the substance = molar mass

So , 1 mole of HCl = 36.45 gram

2 mole of HCl = 2 x 36.45 =72.9 gram

1 mole of CO2 = 44 gram

The given equation is :

$CaCO_{3}+2HCl\rightarrow CO_{2}+H_{2}O$

Here CaCO3 is the excess reagent and HCl is the limiting reagent

2 mole of HCl will produce = 1 mole of CO2

72.9 gram of HCl= 44 gram of CO2

so, 1 gram of HCl =

$\frac{44}{72.9}$ gram of CO2

Here we need to calculate the mass of CO2 in 200 gram of HCl.

So, 200 gram of HCl =

$\frac{44}{72.9}\times 200$ gram CO2

=120.71 gram CO2

this is the theoritical yield of CO2 = 120.71 gram

Experimental yield = 100 gram (given)

The percent yield is calculated by:

$=\frac{Experimental}{Theoritical}\times 100$

$=\frac{100}{120.71}100$

= 82.84%

3.Synthesis Reaction : Those reactions in which two or more substances combine to give a single product.

Here NH3 and HCl are combined and giving only one product = NH4Cl

4.

$2H_{2}+1O_{2}\rightarrow 2H_{2}O$

Hydrogen = H2

Water = H2O

Here Ratio of H2 to H2O is 2:2

5.The balanced equation is :

$1Ca(OH)_{2}+2HCl\rightarrow 1CaCl_{2}+2H_{2}O$

The number of atoms on left side should be equal to the right side:

Ca = 1

H = 4

O = 2

Cl = 2

Here, 2 moles of water(H2O) = 2 moles of HCl

So, 5 moles of water will give = 5 moles of HCl

6.

$2Ag(NO)_{3}+BaCl_{2}\rightarrow 2AgCl_{2}+BaNO_{3}$

Molar mass of AgNO3 = 169.87 g/mol

1 mol of AgNO3 = 169.87 gram

Molar mass of AgCl = 143.32 g/mol

1 mole of AgCl = 143.32 grams

According to the given equation ,

2 mole of AgNO3 will give = 2 mole of AgCl

1 mole of AgNO3 = 1 mole of AgCl

169.87 gram of AgNO3 = 143.32 gram of AgCL

1 gram of AgNO3 =

$\frac{143.32}{169.87}$

5.95 gram of AgNO3 =

$\frac{143.32}{169.87}\times 5.95$

= 5.02 grams

7. The mole ratio of Hydrogen (H2) to Nitrogen (N2):

$N_{2}+3H_{2}\rightarrow 2NH_{3}$

H2 = 3 mole

N2 = 1 mole

[H2]:[N2] = 3:1

8. The moles in a substance can be calculated by using :

$moles=\frac{Mass}{Molar\ mass}$

Mass of N2 = 75 grams (Given)

Molar mass = 28 gram

$moles=\frac{75}{28}$

Moles = 2.678 moles

8 0

3 years ago

Which of the following jobs is a chemist most likely to have?

Alinara [238K]

Formulation Chemist, Cosmetic - Topix Pharmaceuticals - Amityville, NY

The ability to match a prototype is a huge plus. Bench work intesive. Growth

Senior Research and Development Chemist - Bell International Laboratories - Eagan, MN

Independently investigates/resolves research problems/scale up issues. · Ability to communicate with customers on technical aspects as well as

Associate Synthetic Chemist - Arrowhead Pharmaceuticals - Madison, WI

Using a broad portfolio of RNA chemistries and efficient modes of delivery, Arrowhead therapies trigger the RNA interference mechanism to induce

8 0

3 years ago

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