5 The atoms of a certain element each contain 36 protons and 8 valence electrons. Which

Please help Physical Science! Pretty easy.

Alina [70]

A. I think the water may either rise up or it could leak out into the pie pan.

B. The air pressure would increase inside the glass, because you're adding a large amount of air into it.

6 0

4 years ago

The same heat transfer into identical masses of different substances produces different temperature changes. Calculate the final

myrzilka [38]

Answer: final temperatures will be

a) water 21 C

b) concrete 20.005 C

c) steel 20.008 C

d) mercury 53 C

Explanation:

Change in temp dT = dH / (mass x specific heat)

Specific heat of these materials can be found from many sources:

water = 1 kcal / kg C

concrete = 210 kcal / kg C

steel = 114 kcal / kg C

mercury = 0.03 kcal /kg C

So dT (water) from 1 kcal heat into 1 kg water = 1 kcal / (1 kg x 1 kcal/kg C) = 1 C therefore the final temperature is 20 + 1 = 21 C

But dT (steel) = 1 kcal / (1kg x 114 kcal/kg C) = 0.008 C so the final temperature is 20 + 0.008 = 20.008 C

The results for concrete and mercury are calculated in the same way

7 0

3 years ago

A helium balloon has a volume of 2.5 L. When heated to 343.5K the pressure of the gas is 66.7 kPa. How many moles of He gas woul

Lelu [443]

Answer:

0.06mole

Explanation:

Given parameters:

Volume of balloon = 2.5L

T = 343.5K

P = 66.7kPa; in atm gives = 0.66atm

Unknown:

Number of moles of He = ?

Solution:

To solve this problem, we use the ideal gas equation.

It is mathematically expressed as;

Pv = nRT

where p is the pressure

v is the volume

n is the number of moles

R is the gas constant

T is the temperature

0.66 x 2.5 = n x 0.082 x 343.5

n = 0.06mole

8 0

3 years ago

Describe how you would prepare 350 ml of 0.100 m c12h22o11 starting with 3.00l of 1.50 m c12h22o11

Leona [35]

To prepare 350 mL of 0.100 M solution from a 1.50 M solution, we simply have to use the formula:

M1 V1 = M2 V2

So from the formula, we will know how much volume of the 1.50 M we actually need.

1.50 M * V1 = 0.100 M * 350 mL

V1 = 23.33 mL

So we need 23.33 mL of the 1.50 M solution. We dilute it with water to a volume of 350 mL. So water needed is:

350 mL – 23.33 mL = 326.67 mL water

Steps:

1. Take 23.33 mL of 1.50 M solution

<span>2. Add 326.67 mL of water to make 350 mL of 0.100 M solution</span>

7 0

3 years ago

A 1.555-g sample of baking soda decomposes with heat to produce 0.991 g Na2CO3. Refer to Example Exercise 14.l and show the calc

Sunny_sXe [5.5K]

Answer:

a) 101%

b)59.7%

Explanation:

The equation for the thermal decomposition of baking soda is shown;

2NaHCO3 → Na2CO3 + H2O + CO2

Number of moles of baking soda= mass/molar mass= 1.555g/84.007 g/mol = 0.0185 moles

From the reaction equation;

2 moles of baking soda yields 1 mole of sodium carbonate

0.0185 moles of baking soda will yield = 0.0185 moles ×1 /2 = 9.25 ×10^-3 moles of sodium carbonate.

Therefore, mass of sodium carbonate= 9.25 ×10^-3 moles × 106gmol-1= 0.9805 g of sodium carbonate. This is the theoretical yield of sodium carbonate.

%yield = actual yield/theoretical yield ×100

% yield = 0.991/0.9805 ×100

%yield = 101%

Since ;

2NaHCO3 → Na2CO3 + H2O + CO2

And H2O + CO2 ---> H2CO3

Hence I can write, 2NaHCO3 → Na2CO3 + H2CO3

Molar mass of H2CO3= 62.03 gmol-1

Molar mass of baking soda= 84 gmol-1

Therefore, mass of baking soda=

0.325/62.03 × 2 × 84 = 0.88 g of NaHCO3

% of NaHCO3= 0.88/1.473 × 100 = 59.7%

7 0

3 years ago