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Question
Commercial cold packs often contain solid NH4NO3 and a pouch of water. The temperature of the pack drops as the NH4NO3 dissolves in water. Therefore, for the dissolving of NH4NO3 in water,
A) 
Hsoln is negative and Ssoln may be negative or positive.
B) Hsoln is negative and Ssoln is positive.
C) Hsoln is positive and Ssoln may be negative or positive.
D) Hsoln is positive and Ssoln is positive.
Answer
This answer is hidden. It contains 1 characters.
Related questions
Q:
In the following picture of an oxide, darkly-shaded spheres represent oxygen atoms or ions and lightly-shaded spheres represent atoms or ions of a third-row element in its highest oxidation state. Tell whether the oxide is covalent or ionic and whether the oxide is acidic or basic. A) covalent and acidic
B) covalent and basic
C) ionic and acidic
D) ionic and basic
Q:
Picture (a) shows p-orbital overlap between carbon and oxygen atoms; picture (b) shows p-orbital overlap between silicon and oxygen atoms. Based on these pictures, it is expected that
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B) silicon and oxygen form better σ bonds than carbon and oxygen, so Si-O single bonds are stronger than C-O single bonds.
C) carbon and oxygen form better π bonds than silicon and oxygen, so C=O double bonds are stronger than Si=O double bonds.
D) silicon and oxygen form better π bonds than carbon and oxygen, so Si=O double bonds are stronger than C=O double bonds.
Q:
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A) element A
B) element B
C) element C
D) element D
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B) element B
C) element C
D) element D
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The following pictures represent binary hydrides, AHx, where A = Na, Ti, C, or Cl. Lightly-shaded spheres represent H atoms or ions and darkly-colored spheres represent atoms or ions of element A.Which hydride has the lowest melting point?A) hydride (1)B) hydride (2)C) hydride (3)D) hydride (4)
Q:
When 3.600 grams of anhydrous magnesium chloride were exposed to moist air, water was absorbed by the sample. If the resulting hydrated compound has a mass of 4.962 grams, what is the chemical formula of the hydrate?
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Q:
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Q:
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Which element most readily forms nonstoichiometric hydrides?
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Covalent hydrides of the type MH3 are likely to form with elements of what group?
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Q:
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Q:
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Q:
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Q:
The bright colors of anodized titanium are due toA) electrodeposition of organic dyes on the titanium surface.B) the formation of a titanium alloy with chromium and copper.C) iridescence involving the semitransparent outer layer of TiO2.D) trapping of organic dye molecules in a spongy TiO2 matrix.
Q:
Chromium can be electroplated from an aqueous solution containing sulfuric acid and chromic acid, H2CrO4. What current is required to deposit chromium at a rate of 1.25 g/min?
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How many grams of chromium metal are plated out when a constant current of 8.00 A is passed through an aqueous solution containing Cr3+ ions for 40.0 minutes?
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Q:
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Q:
A steel pipe can be protected from corrosion by attaching the pipe to a piece of magnesium because
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B) magnesium is more easily oxidized than iron.
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Q:
Which of the following statements concerning the rusting of iron is false?
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B) The metal is reduced.
C) The rusting of iron requires both oxygen and water.
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Q:
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