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Vera_Pavlovna [14]
3 years ago
12

For a science experiment, a student rubs a mineral against a porcelain plate. The students has just performed

Chemistry
2 answers:
Gemiola [76]3 years ago
6 0
The correct answer is letter B: A streak test.
frosja888 [35]3 years ago
4 0

B.Streak Test.Hope this helps! :)

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A chemist dissolves 867. mg of pure barium hydroxide in enough water to make up 170. mL of solution. Calculate the pH of the sol
Ilya [14]

Answer: The pH of the solution is 11.2

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

Molarity=\frac{n\times 1000}{V_s}

where,

n = moles of solute

V_s = volume of solution in ml

moles of Ba(OH)_2 = \frac{\text {given mass}}{\text {Molar mass}}=\frac{0.867g}{171g/mol}=0.00507mol         (1g=1000mg)

Now put all the given values in the formula of molality, we get

Molarity=\frac{0.00507\times 1000}{170}

Molarity=0.0298

pH or pOH is the measure of acidity or alkalinity of a solution.

pH is calculated by taking negative logarithm of hydrogen ion concentration.

pOH=-\log [OH^-]

Ba(OH)_2\rightarrow Ba^{2+}+2OH^{-}

According to stoichiometry,

1 mole of Ba(OH)_2 gives 2 mole of OH^-

Thus 0.0298 moles of Ba(OH)_2 gives =\frac{2}{1}\times 0.0298=0.0596 moles of OH^-

Putting in the values:

pOH=-\log[0.0596]=2.82

pH+pOH=14

pH=14-2.82

pH=11.2

Thus the pH of the solution is 11.2

8 0
3 years ago
C3H8(g) + 5O2(g) ⟶ 3CO2(g) + 4H2O(g) H = -2220 kJ If 865.9 g of H2O is produced during this combustion, how much heat is generat
dem82 [27]

Answer:

3 × 10⁴ kJ

Explanation:

Step 1: Write the balanced thermochemical equation

C₃H₈(g) + 5 O₂(g) ⟶ 3 CO₂(g) + 4 H₂O(g) ΔH = -2220 kJ

Step 2: Calculate the moles corresponding to 865.9 g of H₂O

The molar mass of H₂O is 18.02 g/mol.

865.9 g × 1 mol/18.02 g = 48.05 mol

Step 3: Calculate the heat produced when 48.05 moles of H₂O are produced

According to the thermochemical equation, 2220 kJ of heat are evolved when 4 moles of H₂O are produced.

48.05 mol × 2220 kJ/4 mol = 2.667 × 10⁴ kJ ≈ 3 × 10⁴ kJ

5 0
2 years ago
A ball is dropped from a height of 20 meters. At what height does the ball have a velocity of 10 meters/second?
musickatia [10]

Answer:

15m

Explanation:

vi = 0

vf = 10

a = -9.8

10^2 = 0 + 2(-9.8)(x2-x1) = -5.1

20-5.1 = 14.9m = 15m

3 0
2 years ago
How does the comic strip define a polar molecule
zmey [24]

The answer is: A molecule with a difference in electrical charge between two ends.

Electronegativity (χ) is a property that describes the tendency of an atom to attract a shared pair of electrons.

Atoms with higher electronegativity attracts more electrons towards it, electrons are closer to that atom.

For example fluorine has electronegativity approximately χ = 4 and oxygen χ = 3,5, fluorine attracts electron and he has negative charge and oxygen has positive charge.

4 0
3 years ago
When a bimetallic bar made of copper and iron strips is heated, the bar bends toward the iron strip. the reason for this is?
Digiron [165]
<span>iron gets hotter before copper.</span>
7 0
3 years ago
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