What period is Zn (zinc) in? O A. 2A O B. 12 O C. 30 D. 4

A motor uses the attracting and repelling forces of magnets to create rotational motion. What type of energy results from this p

zavuch27 [327]

b) Mechanical

:D Hope it helps!

7 0

3 years ago

Read 2 more answers

Multiply or divide the following me 364.51 m - 63.46 s 3

IgorC [24]

Answer:

In multiplication the answer can contain only the least significant figures as present in any of its values . Here 93.4

6 0

3 years ago

2.61 kilograms of water in a container have a pressure of 200 kPa and temperature of 200°C . What is the volume of this containe

Arisa [49]

Answer: The volume of the container is $2.8497m^3$

Explanation:

To calculate the volume of water, we use the equation given by ideal gas, which is:

$PV=nRT$

or,

$PV=\frac{m}{M}RT$

where,

P = pressure of container = 200 kPa

V = volume of container = ? L

m = Given mass of water = 2.61 kg = 2610 g (Conversion factor: 1kg = 1000 g)

M = Molar mass of water = 18 g/mol

R = Gas constant = $8.31\text{L kPa }mol^{-1}K^{-1}$

T = temperature of container = $200^oC=[200+273]K=473K$

Putting values in above equation, we get:

$200kPa\times V=\frac{2610g}{18g/mol}\times 8.31\text{L kPa }\times 473K\\\\V=2849.7L$

Converting this into cubic meter, we use the conversion factor:

$1m^3=1000L$

So, $\Rightarrow \frac{1m^3}{1000L}\times 2849.7L$

$\Rightarrow 2.8497m^3$

Hence, the volume of the container is $2.8497m^3$

6 0

3 years ago

When 16.9 g KOH is dissolved in 90.8 g of water in a coffee-cup calorimeter, the temperature rises from 18.5 °C to 34.27 °C. Wha

juin [17]

Answer:

-431.5 J/g

Explanation:

Mass of solution = Mass of solute + mass of solvent

Solute is KOH while solvent is water.

Mass of KOH = 16.9 g

Mass of water = 90.8 g

Mass of solution = 16.9 + 90.8

= 107.7 g

Change in temperature (Δt) = 34.27 - 18.5

= 16.2 °C

Heat required to raise the temperature of water is released by dissolving KOH.

Therefore,

Heat released by KOH = m × s× Δt

= 107.7 × 4.18 × 16.2

= 7293 J

Heat released by per g KOH = 7293 J/16.9 g

= 431.5 J/g

As heat is released therefore, enthalpy change would be negative.

Enthalpy change of KOH = -431.5 J/g

4 0

3 years ago

Pyridine, C5H5N, is a bad-smelling liquid that is a weak base in water. Its pKb is 8.77. What is the pH of a 0.20 M aqueous solu

kari74 [83]

Answer:

pH = 9.26

Explanation:

Let's make the reaction of this weak base:

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻ Kb

We do not know the Kb, but we can discover it from pKb

Kb = 10^⁻pKb → 10⁻⁸'⁷⁷ = 1.70×10⁻⁹

So, let's make the expression for Kb

Kb = [OH⁻] . [C₅H₅NH⁺] / [C₅H₅N]

In the equilibrum, we would have 0.20 moles from the begining - x (react)

So we would proudce x moles of OH⁻ and x moles of C₅H₅NH⁺.

In conclussion:

1.70×10⁻⁹ = x . x / (0.20 - x)

To avoid the quadratic formula we can miss the x from the substraction

1.70×10⁻⁹ = x² / 0.20

1.70×10⁻⁹ . 0.20 = x²

We avoid the x from the (0.20-x), because the base is so concentrated, and Kb is very small.

x = √(1.70×10⁻⁹ . 0.20) → 1.84×10⁻⁵

That's the value of [OH⁻], so we can calculate pOH

- log [OH⁻] = pOH → - log 1.84×10⁻⁵ = 4.73

Then pH = 14 - pOH

14 - 4.73 = 9.26

4 0

4 years ago